Display with reflective spatial light modulator and a film-based lightguide frontlight folded behind the modulator to receive light from a light source positioned on an electrical display connector

ABSTRACT

A display includes a reflective spatial light modulator and a frontlight formed from a film having a light mixing region positioned along the film between a light emitting region and an array of coupling lightguides. In one embodiment, the light mixing region of the film and an electrical display connector are folded behind an active display area of the reflective spatial light modulator such that a light source positioned on the electrical display connector emits light into the array of coupling lightguides. In one embodiment, the light source and the reflective spatial light modulator are electrically driven by electrical connections on the flexible electrical display connector.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/988,476 entitled “Light emitting device comprising a lightguide filmand aligned coupling lightguides” filed Aug. 9, 2013, which was theNational Stage of International Application No. PCT/US2011/61528entitled “Light emitting device comprising a lightguide film and alignedcoupling lightguides” filed Nov. 18, 2011 which claims the benefit ofU.S. Provisional Application No. 61/415,250, entitled “Light emittingdevice comprising a lightguide film and light turning optical element,”filed Nov. 18, 2010, the entire contents of each are incorporated byreference herein.

TECHNICAL FIELD

The subject matter disclosed herein generally relates to light emittingdevices such as light fixtures, backlights, frontlights, light emittingsigns, passive displays, and active displays and their components andmethod of manufacture.

BACKGROUND

Conventionally, in order to reduce the thickness of displays andbacklights, edge-lit configurations using rigid lightguides have beenused to receive light from the edge of and direct light out of a largerarea face. These types of light emitting devices are typically housed inrelatively thick, rigid frames that do not allow for component or deviceflexibility and require long lead times for design changes. The volumeof these devices remains large and often includes thick or large framesor bezels around the device. The thick lightguides (typically 2millimeters (mm) and larger) limit the design configurations, productionmethods, and illumination modes.

The ability to further reduce the thickness and overall volume of thesearea light emitting devices has been limited by the ability to couplesufficient light flux into a thinner lightguide. Typical LED lightsources have a light emitting area dimension of at least 1 mm, and thereis often difficulty controlling the light entering, propagating through,and coupled out of the 2 mm lightguide to meet design requirements. Thedisplays incorporating the 2 mm lightguides are typically limited tosmall displays having a diagonal dimension of 33 centimeters (cm) orless. Many system sizes are thick due to designs that use large lightsources and large input coupling optics or methods. Some systems usingone lightguide per pixel (such as fiber optic based systems) require alarge volume and have low alignment tolerances. In production, thinlightguides have been limited to coatings on rigid wafers for integratedoptical components.

SUMMARY

A display includes a reflective spatial light modulator and a frontlightformed from a film having a light mixing region positioned along thefilm between a light emitting region and an array of couplinglightguides. In one embodiment, the light mixing region of the film andan electrical display connector are folded behind an active display areaof the reflective spatial light modulator such that a light sourcepositioned on the electrical display connector emits light into thearray of coupling lightguides. In one embodiment, the light source andthe reflective spatial light modulator are electrically driven byelectrical connections on the flexible electrical display connector. Inone embodiment, a light emitting device comprises a light source havingan optical axis; a relative position maintaining element; and alightguide comprising a film having a thickness not greater than 0.5millimeters. The lightguide includes a lightguide region and an array ofcoupling lightguides continuous with the lightguide region. Eachcoupling lightguide of the array of coupling lightguides terminates inan edge and at least one of the array of coupling lightguides is foldedat least partially around the relative position maintaining element suchthat the edges of the array of coupling lightguides form a stackdefining a light input surface. Light from the light source enters intothe light input surface and propagates by total internal reflectionwithin each coupling lightguide to the lightguide region. The relativeposition maintaining element extends past the light input surface in adirection parallel to the optical axis.

In another embodiment, a light emitting device comprises a light sourceand a lightguide comprising a film having a thickness not greater than0.5 millimeters. The lightguide includes a lightguide region and anarray of coupling lightguides continuous with the lightguide region.Each coupling lightguide of the array of coupling lightguides terminatesin an edge and at least one of the array of coupling lightguides isfolded such that the edges of the array of coupling lightguides form astack defining a light input surface.

In another embodiment, a light emitting device comprises a light sourceand a lightguide formed from a film having a thickness not greater than0.5 millimeters. The lightguide includes a lightguide region and anarray of coupling lightguides continuous with the lightguide region.Each coupling lightguide of the array of coupling lightguides terminatesin an edge and at least one of the array of coupling lightguides isfolded such that the edges of the array of coupling lightguides form astack defining a light input surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of one embodiment of a light emitting devicecomprising a light input coupler disposed on one side of a lightguide.

FIG. 2 is a perspective view of one embodiment of a light input couplerwith coupling lightguides folded in the −y direction.

FIG. 3 is a top view of one embodiment of a light emitting device withthree light input couplers on one side of a lightguide.

FIG. 4 is a top view of one embodiment of a light emitting device withtwo light input couplers disposed on opposite sides of a lightguide.

FIG. 5 is a top view of one embodiment of a light emitting device withtwo light input couplers disposed on the same side of a lightguidewherein the optical axes of the light sources are oriented substantiallytoward each other.

FIG. 6 is a cross-sectional side view of one embodiment of a lightemitting device with a substantially flat light input surface comprisedof flat edges of a coupling lightguide disposed to receive light from alight source.

FIG. 7 is a cross-sectional side view of one embodiment of a lightemitting device with a light input coupler with a light input surfacewith refractive and flat surface features on the light input surfacewherein light totally internal reflects on some outer surfaces similarto a hybrid refractive-TIR Fresnel lens.

FIG. 8 is a cross-sectional side view of one embodiment of a lightemitting device wherein the coupling lightguides and the light inputsurface are optically coupled to the light source.

FIG. 9 is a cross-sectional side view of one embodiment of a lightemitting device wherein the coupling lightguides are held in place by asleeve and the edge surfaces are effectively planarized by an opticaladhesive or material such as a gel between the ends of the couplinglightguides and the sleeve with a flat outer surface adjacent the lightsource.

FIG. 10 is a top view of one embodiment of a backlight emitting red,green, and blue light.

FIG. 11 is a cross-sectional side view of one embodiment of a lightemitting device comprising a light input coupler and lightguide with areflective optical element disposed adjacent a surface.

FIG. 12 is a cross-sectional side view of a region of one embodiment ofa display illuminated by red, green, and blue lightguides wherein thelocations of the pixels of the display correspond to light emittingregions of the lightguide separated by color.

FIG. 13 is a cross-sectional side view of a region of one embodiment ofa color sequential display.

FIG. 14 is a cross-sectional side view of a region of one embodiment ofa spatial display (such as a liquid crystal display).

FIG. 15 is a cross-sectional side view of a region of one embodiment ofa display comprising a white light source backlight.

FIG. 16 is a cross-sectional side view of a region of one embodiment ofa display comprising a wavelength converting backlight.

FIG. 17 is a cross-sectional side view of a region of one embodiment ofa display with a backlight comprising a plurality of lightguidesemitting different colored light in predetermined spatial patterns.

FIG. 18 is a top view of one embodiment of a light emitting devicecomprising two light input couplers with light sources on the same edgein the middle region oriented in opposite directions.

FIG. 19 is a top view of one embodiment of a light emitting devicecomprising one light input coupler with coupling lightguides foldedtoward the −y direction and then folded in the +z direction toward asingle light source.

FIG. 20 is a cross-sectional side view of one embodiment of a displayoptically coupled to a film lightguide.

FIG. 21 is a cross-sectional side view of one embodiment of a spatialdisplay comprising a film-based lightguide frontlight optically coupledto a reflective spatial light modulator.

FIG. 22 is a cross-sectional side view of one embodiment of a spatialdisplay comprising a front-lit film lightguide disposed adjacent to areflective spatial light modulator.

FIG. 23 is a cross-sectional side view of one embodiment of a spatialdisplay comprising a front-lit film lightguide optically coupled to areflective spatial light modulator with light extraction features on aside of the lightguide nearest the reflective spatial light modulator.

FIG. 24 is a cross-sectional side view of one embodiment of a spatialdisplay comprising a front-lit film lightguide disposed within areflective spatial light modulator.

FIG. 25 is a cross-sectional side view of one embodiment of a lightemitting device comprising a light input coupler disposed adjacent alight source with a light collimating optical element.

FIG. 26 is a perspective view of one embodiment of a light emittingdevice comprising light coupling lightguides and a light source orientedat an angle to the x, y, and z axis.

FIG. 27 is a perspective view of one embodiment of a light emittingdevice wherein the coupling lightguides are optically coupled to asurface of a lightguide.

FIG. 28 is a perspective view of one embodiment of a light emittingdevice wherein the coupling lightguides are optically coupled to theedge of a lightguide.

FIG. 29a is a perspective view of one embodiment for manufacturing alight input coupler comprising an array of coupling lightguides that aresubstantially within the same plane as the lightguide and the couplinglightguides are regions of a light transmitting film comprising twolinear fold regions.

FIG. 29b is a perspective view of one embodiment for manufacturing aninput coupler and lightguide comprising translating one of the linearfold regions of FIG. 29 a.

FIG. 29c is a perspective view of one embodiment for manufacturing aninput coupler and lightguide comprising translating one of the linearfold regions of FIG. 29 b.

FIG. 29d is a perspective view of one embodiment for manufacturing aninput coupler and lightguide comprising translating one of the linearfold regions of FIG. 29 c.

FIG. 29e is a perspective view of one embodiment for manufacturing aninput coupler and lightguide comprising translating one of the linearfold regions of FIG. 29 d.

FIG. 30 is a cross-sectional side view of a region of one embodiment ofa reflective display comprising a backlight disposed between the lightmodulating pixels and the reflective element.

FIG. 31 is a top view of one embodiment of an input coupler andlightguide wherein the array of coupling lightguides has non-parallelregions.

FIG. 32 is a perspective top view of a portion of the input coupler andlightguide of FIG. 31 with the coupling lightguides folded.

FIG. 33 is a perspective view of one embodiment of a light input couplerand lightguide comprising a relative position maintaining elementdisposed proximate a linear fold region.

FIG. 34 is a top view of one embodiment of a light input coupler andlightguide comprising bundles of coupling lightguides that are foldedtwice and recombined in a plane substantially parallel to the film-basedlightguide.

FIG. 35a is a top view of one embodiment of a light input coupler andlightguide comprising bundles of coupling lightguides that are foldedupwards (+z direction) and combined in a stack that is substantiallyperpendicular to the plane of the film-based lightguide.

FIG. 35b is a magnification of the region of FIG. 35a comprising theupward folds of the coupling lightguides.

FIG. 36 is a top view of one embodiment of a light emitting devicecomprising a lenticular lens array film.

FIG. 37 is a cross-sectional side view of one embodiment of a lenticularlens array film comprising light extraction features.

FIG. 38 is a cross-sectional side view of a section of one embodiment ofa display comprising a multi-layer lenticular lens array film.

FIG. 39 is a top view of one embodiment of a light emitting device withan un-folded lightguide comprising fold regions.

FIG. 40 is a perspective view of the light emitting device of FIG. 39with the lightguide being folded.

FIG. 41 is a perspective view of the light emitting device of FIG. 39folded with the lightguide comprising overlapping folded regions.

FIG. 42 is an elevated view of one embodiment of a film-based lightguidecomprising a first light emitting region disposed to receive light froma first set of coupling lightguides and a second light emitting regiondisposed to receive light from a second set of coupling lightguides.

FIG. 43 is an elevated view of the film-based lightguide of FIG. 42 withthe lightguides folded.

FIG. 44 is a cross-sectional side view of one embodiment of a lightemitting device with optical redundancy comprising two lightguidesstacked in the z direction.

FIG. 45 is a cross-sectional side view of one embodiment of a lightemitting device with a first light source and a second light sourcethermally coupled to a first thermal transfer element.

FIG. 46 is a top view of one embodiment of a light emitting devicecomprising coupling lightguides with a plurality of first reflectivesurface edges and a plurality of second reflective surface edges withineach coupling lightguide.

FIG. 47 is an enlarged perspective view of the input end of the couplinglightguides of FIG. 46.

FIG. 48 is a cross-sectional side view of the coupling lightguides andlight source of one embodiment of a light emitting device comprisingindex matching regions disposed between the core regions of the couplinglightguides.

FIG. 49 is a top view of one embodiment of a film-based lightguidecomprising an array of tapered coupling lightguides.

FIG. 50 is a perspective top view of a light emitting device of oneembodiment comprising the film-based lightguide of FIG. 49 and a lightsource.

FIG. 51 is a perspective top view of an embodiment of a light emittingdevice comprising the light emitting device of FIG. 50 wherein thetapered coupling lightguides and light source are folded behind thelight emitting region.

FIG. 52 is a top view of one embodiment of a film-based lightguidecomprising an array of angled, tapered coupling lightguides.

FIG. 53 is a perspective top view of a light emitting device of oneembodiment comprising the film-based lightguide of FIG. 52.

FIG. 54 is a top view of one embodiment of a film-based lightguidecomprising a first and second array of angled, tapered couplinglightguides.

FIG. 55 is a perspective top view of a light emitting device of oneembodiment comprising the film-based lightguide of FIG. 54.

FIG. 56 is a top view of one embodiment of a light emitting devicecomprising a lightguide, coupling lightguides and a curved mirror.

FIG. 57 is a top view of one embodiment of a light emitting devicecomprising a lightguide, coupling lightguides, and a curved mirror withtwo curved regions.

FIG. 58 is a top view of one embodiment of a light emitting devicecomprising a lightguide and two light input couplers comprising couplinglightguides that have been folded behind the light emitting region ofthe light emitting device.

FIG. 59 is a top view of one embodiment of a light emitting devicecomprising a lightguide with coupling lightguides on two orthogonalsides.

FIG. 60 is a cross-sectional side view of a portion of a light emittingdevice of one embodiment comprising a lightguide and a light inputcoupler wherein a low contact area cover is physically coupled to thelight input coupler.

FIG. 61 shows an enlarged portion of FIG. 60 of the region of thelightguide in contact with the low contact area cover.

FIG. 62 is a side view of a portion of a light emitting device of oneembodiment comprising a lightguide and a light input coupler protectedby a low contact area cover.

FIG. 63 is a perspective view of a portion of a film-based lightguide ofone embodiment comprising coupling lightguides comprising two flanges oneither side of the end region of the coupling lightguides.

FIG. 64 is a perspective view of one embodiment of a film-basedlightguide comprising a light input coupler and lightguide comprising arelative position maintaining element disposed proximal to a linear foldregion.

FIG. 65 is a perspective view of one embodiment of relative positionmaintaining element comprising rounded angled edge surfaces.

FIG. 66 is a perspective view of one embodiment of relative positionmaintaining element comprising rounded angled edge surfaces and arounded tip.

FIG. 67 is a perspective view of a portion of a film-based lightguide ofone embodiment comprising coupling lightguides comprising two flanges oneither side of the end region of the coupling lightguides.

FIG. 68 is a perspective view of a portion of the light emitting deviceof the embodiment illustrated in FIG. 62.

FIG. 69 is a top view of one embodiment of a light emitting device withtwo light input couplers, a first light source, and a second lightsource disposed on opposite sides of a lightguide.

FIG. 70 is a perspective view of one embodiment of a light emittingdevice comprising a lightguide, a light input coupler, and a lightreflecting film disposed between the light input coupler and the lightemitting region.

FIG. 71 is a top view of a region of one embodiment of a light emittingdevice comprising a stack of coupling lightguides disposed to receivelight from a light collimating optical element and a light source.

FIG. 72 is a cross-sectional side view of the embodiment shown in FIG.71.

FIG. 73 is a top view of a region of one embodiment of a light emittingdevice comprising a stack of coupling lightguides physically coupled toa collimating optical element.

FIG. 74 is a top view of a region of one embodiment of a light emittingdevice comprising a light source adjacent a light turning opticalelement optically coupled to a stack of coupling lightguides.

FIG. 75a is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed adjacent a lateral edge of astack of coupling lightguides with light turning optical edges.

FIG. 75b is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed adjacent the light inputsurface edge of the extended region of a stack of coupling lightguideswith light turning optical edges.

FIG. 76 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into two lightturning optical elements that are optically coupled to two stacks ofcoupling lightguides using an optical adhesive.

FIG. 77 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into abi-directional light turning optical element optically coupled to twostacks of coupling lightguides.

FIG. 78 is a top view of a region of one embodiment of a light emittingdevice comprising two light sources disposed to couple light into abi-directional light turning optical element optically coupled to twostacks of coupling lightguides.

FIG. 79 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into twostacks of coupling lightguides with light turning optical edges.

FIG. 80 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into twooverlapping stacks of coupling lightguides with light turning opticaledges.

FIG. 81 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into a stackof coupling lightguides with light turning optical edges wherein thecoupling lightguides have tabs with tab alignment holes.

FIG. 82 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into a stackof coupling lightguides with light turning optical edges andregistration holes in a low light flux density region.

FIG. 83 is a top view of a region of one embodiment of a light emittingdevice comprising a light source disposed to couple light into a stackof coupling lightguides with a light source overlay tab region for lightsource registration.

FIG. 84 is a top view of one embodiment of a lightguide comprisingcoupling lightguides with light turning optical edges.

FIG. 85 is a top view of one embodiment of a light emitting devicecomprising the lightguide of FIG. 84 with the coupling lightguidesfolded such that they extend past a lateral edge.

FIG. 86 is a top view of one embodiment of a lightguide comprising anon-folded coupling lightguide.

FIG. 87 is a top view of one embodiment of a light emitting devicecomprising the lightguide of FIG. 86 wherein the coupling lightguidesare folded.

FIG. 88 is a top view of one embodiment of a lightguide comprisingcoupling lightguides with light collimating optical edge regions andlight turning optical edge regions.

FIG. 89 is a top view of one embodiment of a light emitting devicecomprising the film-based lightguide of FIG. 88 wherein couplinglightguides are folded.

FIG. 90 is a top view of one embodiment of a lightguide comprisingcoupling lightguides with extended regions.

FIG. 91 is a top view of one embodiment of the lightguide of FIG. 90with the coupling lightguides folded.

FIG. 92 is a top view of one embodiment of a lightguide comprisingcoupling lightguides with light turning optical edges turning light intwo directions and a non-folded coupling lightguide.

FIG. 93 is a perspective top view of one embodiment of a light emittingdevice comprising the film-based lightguide of FIG. 92 with the couplinglightguides from each side grouped together.

FIG. 94 is a perspective top view of one embodiment of a light emittingdevice comprising the film-based lightguide of FIG. 92 with the couplinglightguides from the sides interleaved in a stack.

FIG. 95 is a top view of one embodiment of a film-based lightguidecomprising coupling lightguides with light turning optical edgesextended in shapes inverted along a first direction.

FIG. 96 is a perspective view of a lightguide comprising one embodimentof the lightguide of FIG. 95 folded to form two stacks of couplinglightguides.

FIG. 97 is a top view of one embodiment of a film-based lightguidecomprising coupling lightguides with light turning optical edges, lightcollimating optical edges, and light source overlay tab regionscomprising alignment cavities.

FIG. 98 is a top view of one embodiment of a light emitting devicecomprising the film-based lightguide of FIG. 97 folded to a stack ofcoupling lightguides positioned over a light source and guided in the zdirection by an alignment guide.

FIG. 99 is a side view of the light emitting device embodiment of FIG.98 in the region near the light source.

FIG. 100 is a side view of a region of one embodiment of a lightemitting device with coupling lightguides with alignment cavities thatdo not extend to fit completely over the alignment guide.

FIG. 101 is a cross-sectional side view of a region of one embodiment ofa light emitting device comprising coupling lightguides with interiorlight directing edges.

FIG. 102 is a cross-sectional side view of one embodiment of a lightemitting display comprising a reflective spatial light modulator and afilm-based lightguide frontlight adhered to a flexible connector.

FIG. 103 is a cross-sectional side view of one embodiment of a lightemitting display comprising a lightguide that further functions as a topsubstrate for a reflective spatial light modulator.

FIG. 104 is a perspective view of one embodiment of a light emittingdevice comprising a film-based lightguide that further functions as atop substrate for the reflective spatial light modulator with the lightsource disposed on a circuit board physically coupled to the flexibleconnector.

FIG. 105 is a perspective view of one embodiment of a light emittingdisplay comprising a reflective spatial light modulator and a film-basedlightguide adhered to a flexible connector with the light sourcephysically coupled to a flexible connector.

FIG. 106 is a cross-sectional side view of one embodiment of a displaycomprising the light emitting device of FIG. 104 further comprising aflexible touchscreen.

FIG. 107 is a perspective view of one embodiment of a light emittingdevice with the flexible touchscreen between the film-based lightguideand the reflective spatial light modulator.

FIG. 108 is a perspective view of one embodiment of a reflective displaycomprising a flexible display driver connector and a flexible film-basedlightguide frontlight.

FIG. 109 is a perspective view of one embodiment of a reflective displaycomprising a flexible display driver connector and a flexible film-basedlightguide frontlight with a light source disposed on a flexibletouchscreen film.

FIG. 110 is a top view of one embodiment of a film-based lightguidecomprising an array of coupling lightguides wherein each couplinglightguide further comprises a sub-array of coupling lightguides.

FIG. 111 is a perspective top view of one embodiment of a light emittingdevice comprising the film-based lightguide of FIG. 110 wherein thecoupling lightguides are folded.

FIG. 112 is a cross-sectional side view of a region of one embodiment ofa light emitting device comprising a stacked array of couplinglightguides with core regions comprising vertical light turning opticaledges.

FIG. 113 is a cross-sectional side view of a region of one embodiment ofa light emitting device comprising a stacked array of couplinglightguides with core regions comprising vertical light turning opticaledges and vertical light collimating optical edges.

FIG. 114 is a cross-sectional side view of a region of one embodiment ofa light emitting device comprising a stacked array of couplinglightguides with a cavity and core regions comprising vertical lightturning optical edges and light collimating optical edges

FIG. 115 is a perspective view of a region of one embodiment of a lightemitting device comprising a stacked array of coupling lightguidesdisposed within an alignment cavity of a thermal transfer element.

FIG. 116 is a side view of a region of one embodiment of a lightemitting device comprising a stacked array of coupling lightguidesdisposed within an alignment guide with an extended alignment arm and analignment cavity.

FIG. 117 is a perspective view of one embodiment of a light emittingdevice comprising film-based lightguide and a light reflecting opticalelement that is also a light collimating optical element and lightblocking element.

DETAILED DESCRIPTION

The features and other details of several embodiments will now be moreparticularly described. It will be understood that particularembodiments described herein are shown by way of illustration and not aslimitations. The principal features can be employed in variousembodiments without departing from the scope of any particularembodiment. All parts and percentages are by weight unless otherwisespecified.

Definitions

“Electroluminescent sign” is defined herein as a means for displayinginformation wherein the legend, message, image or indicia thereon isformed by or made more apparent by an electrically excitable source ofillumination. This includes illuminated cards, transparencies, pictures,printed graphics, fluorescent signs, neon signs, channel letter signs,light box signs, bus-stop signs, illuminated advertising signs, EL(electroluminescent) signs, LED signs, edge-lit signs, advertisingdisplays, liquid crystal displays, electrophoretic displays, point ofpurchase displays, directional signs, illuminated pictures, and otherinformation display signs. Electroluminescent signs can be self-luminous(emissive), back-illuminated (back-lit), front illuminated (front-lit),edge-illuminated (edge-lit), waveguide-illuminated or otherconfigurations wherein light from a light source is directed throughstatic or dynamic means for creating images or indicia.

“Optically coupled” as defined herein refers to coupling of two or moreregions or layers such that the light passing from one region to theother is not substantially reduced by Fresnel interfacial reflectionlosses due to differences in refractive indices between the regions.“Optical coupling” methods include methods of coupling wherein the tworegions coupled together have similar refractive indices or using anoptical adhesive with a refractive index substantially near or betweenthe refractive index of the regions or layers. Examples of “opticalcoupling” include, without limitation, lamination using an index-matchedoptical adhesive, coating a region or layer onto another region orlayer, or hot lamination using applied pressure to join two or morelayers or regions that have substantially close refractive indices.Thermal transferring is another method that can be used to opticallycouple two regions of material. Forming, altering, printing, or applyinga material on the surface of another material are other examples ofoptically coupling two materials. “Optically coupled” also includesforming, adding, or removing regions, features, or materials of a firstrefractive index within a volume of a material of a second refractiveindex such that light propagates from the first material to the secondmaterial. For example, a white light scattering ink (such as titaniumdioxide in a methacrylate, vinyl, or polyurethane based binder) may beoptically coupled to a surface of a polycarbonate or silicone film byinkjet printing the ink onto the surface. Similarly, a light scatteringmaterial such as titanium dioxide in a solvent applied to a surface mayallow the light scattering material to penetrate or adhere in closephysical contact with the surface of a polycarbonate or silicone filmsuch that it is optically coupled to the film surface or volume.

“Light guide” or “waveguide” refers to a region bounded by the conditionthat light rays propagating at an angle that is larger than the criticalangle will reflect and remain within the region. In a light guide, thelight will reflect or TIR (totally internally reflect) if the angle (a)satisfies the condition

${\alpha > {\sin^{- 1}( \frac{n_{2}}{n_{1}} )}},$where n₁ is the refractive index of the medium inside the light guideand n₂ is the refractive index of the medium outside the light guide.Typically, n₂ is air with a refractive index of n≈1; however, high andlow refractive index materials can be used to achieve light guideregions. The light guide may comprise reflective components such asreflective films, aluminized coatings, surface relief features, andother components that can redirect or reflect light. The light guide mayalso contain non-scattering regions such as substrates. Light can beincident on a lightguide region from the sides or below and surfacerelief features or light scattering domains, phases or elements withinthe region can direct light into larger angles such that it totallyinternally reflects or into smaller angles such that the light escapesthe light guide. The light guide does not need to be optically coupledto all of its components to be considered as a light guide. Light mayenter from any face (or interfacial refractive index boundary) of thewaveguide region and may totally internally reflect from the same oranother refractive index interfacial boundary. A region can befunctional as a waveguide or lightguide for purposes illustrated hereinas long as the thickness is larger than the wavelength of light ofinterest. For example, a light guide may be a 5 micrometer region orlayer of a film or it may be a 3 millimeter sheet comprising a lighttransmitting polymer.

“In contact” and “disposed on” are used generally to describe that twoitems are adjacent one another such that the whole item can function asdesired. This may mean that additional materials can be present betweenthe adjacent items, as long as the item can function as desired.

A “film” as used herein refers to a thin extended region, membrane, orlayer of material.

A “bend” as used herein refers to a deformation or transformation inshape by the movement of a first region of an element relative to asecond region, for example. Examples of bends include the bending of aclothes rod when heavy clothes are hung on the rod or rolling up a paperdocument to fit it into a cylindrical mailing tube. A “fold” as usedherein is a type of bend and refers to the bend or lay of one region ofan element onto a second region such that the first region covers thesecond region. An example of a fold includes bending a letter andforming creases to place it in an envelope. A fold does not require thatall regions of the element overlap. A bend or fold may be a change inthe direction along a first direction along a surface of the object. Afold or bend may or may not have creases and the bend or fold may occurin one or more directions or planes such as 90 degrees or 45 degrees. Abend or fold may be lateral, vertical, torsional, or a combinationthereof.

Light Emitting Device

In one embodiment, a light emitting device comprises a first lightsource, a light input coupler, a light mixing region, and a lightguidecomprising a light emitting region with a light extraction feature. Inone embodiment, the first light source has a first light source emittingsurface, the light input coupler comprises an input surface disposed toreceive light from the first light source and transmit the light throughthe light input coupler by total internal reflection through a pluralityof coupling lightguides. In this embodiment, light exiting the couplinglightguides is re-combined and mixed in a light mixing region anddirected through total internal reflection within a lightguide orlightguide region. Within the lightguide, a portion of incident light isdirected within the light extracting region by light extracting featuresinto a condition whereupon the angle of light is less than the criticalangle for the lightguide and the directed light exits the lightguidethrough the lightguide light emitting surface.

In a further embodiment, the lightguide is a film with light extractingfeatures below a light emitting device output surface within the filmand film is separated into coupling lightguide strips which are foldedsuch that they form a light input coupler with a first input surfaceformed by the collection of edges of the coupling lightguides.

In one embodiment, the light emitting device has an optical axis definedherein as the direction of peak luminous intensity for light emittingfrom the light emitting surface or region of the device for devices withoutput profiles with one peak. For optical output profiles with morethan one peak and the output is symmetrical about an axis, such as witha “batwing” type profile, the optical axis of the light emitting deviceis the axis of symmetry of the light output. In light emitting deviceswith angular luminous intensity optical output profiles with more thanone peak which are not symmetrical about an axis, the light emittingdevice optical axis is the angular weighted average of the luminousintensity output. For non-planar output surfaces, the light emittingdevice optical axis is evaluated in two orthogonal output planes and maybe a constant direction in a first output plane and at a varying anglein a second output plane orthogonal to the first output plane. Forexample, light emitting from a cylindrical light emitting surface mayhave a peak angular luminous intensity (thus light emitting deviceoptical axis) in a light output plane that does not comprise the curvedoutput surface profile and the angle of luminous intensity could besubstantially constant about a rotational axis around the cylindricalsurface in an output plane comprising the curved surface profile, andthus the peak angular intensity is a range of angles. When the lightemitting device has a light emitting device optical axis in a range ofangles, the optical axis of the light emitting device comprises therange of angles or an angle chosen within the range. The optical axis ofa lens or element is the direction of which there is some degree ofrotational symmetry in at least one plane and as used herein correspondsto the mechanical axis. The optical axis of the region, surface, area,or collection of lenses or elements may differ from the optical axis ofthe lens or element, and as used herein is dependent on the incidentlight angular and spatial profile, such as in the case of off-axisillumination of a lens or element.

Light Input Coupler

In one embodiment, a light input coupler comprises a plurality ofcoupling lightguides disposed to receive light emitting from a lightsource and channel the light into a lightguide. In one embodiment, theplurality of coupling lightguides are strips cut from a lightguide filmsuch that they remain un-cut on at least one edge but can be rotated orpositioned (or translated) substantially independently from thelightguide to couple light through at least one edge or surface of thestrip. In another embodiment, the plurality of coupling lightguides arenot cut from the lightguide film and are separately optically coupled tothe light source and the lightguide. In one embodiment, the light inputcoupler comprises at least one light source optically coupled to thecoupling lightguides which join together in a light mixing region. Inanother embodiment, the light input coupler is a collection of stripsections cut from a region film which are arranged in a grouping suchthat light may enter through the edge of a grouping or arrangement ofstrips. In another embodiment, the light emitting device comprises alight input coupler comprising a core region of a core material and acladding region or cladding layer of a cladding material on at least oneface or edge of the core material with a refractive index less than thecore material. In other embodiment, the light input coupler comprises aplurality of coupling lightguides wherein a portion of light from alight source incident on the face of at least one strip is directed intothe lightguide such that it propagates in a waveguide condition. Thelight input coupler may also comprise at least one selected from thegroup: a strip folding device, a strip holding element, and an inputsurface optical element.

Light Source

In one embodiment, a light emitting device comprises at least one lightsource selected from a group: fluorescent lamp, cylindrical cold-cathodefluorescent lamp, flat fluorescent lamp, light emitting diode, organiclight emitting diode, field emissive lamp, gas discharge lamp, neonlamp, filament lamp, incandescent lamp, electroluminescent lamp,radiofluorescent lamp, halogen lamp, incandescent lamp, mercury vaporlamp, sodium vapor lamp, high pressure sodium lamp, metal halide lamp,tungsten lamp, carbon arc lamp, electroluminescent lamp, laser, photonicbandgap based light source, quantum dot based light source, highefficiency plasma light source, microplasma lamp. The light emittingdevice may comprise a plurality of light sources arranged in an array,on opposite sides of lightguide, on orthogonal sides of a lightguide, on3 or more sides of a lightguide, or on 4 sides of a substantially planerlightguide. The array of light sources may be a linear array withdiscrete LED packages comprises at least one LED die. In anotherembodiment, a light emitting device comprises a plurality of lightsources within one package disposed to emit light toward a light inputsurface. In one embodiment, the light emitting device comprises 1, 2, 3,4, 5, 6, 8, 9, 10, or more than 10 light sources.

In one embodiment, a light emitting device comprises at least onebroadband light source that emits light in a wavelength spectrum largerthan 100 nanometers. In another embodiment, a light emitting devicecomprises at least one narrowband light source that emits light in anarrow bandwidth less than 100 nanometers. In another embodiment, alight emitting device comprises at least one broadband light source thatemits light in a wavelength spectrum larger than 100 nanometers or atleast one narrowband light source that emits light in a narrow bandwidthless than 100 nanometers. In one embodiment a light emitting devicecomprises at least one narrowband light source with a peak wavelengthwithin a range selected from the group: 300 nm-350 nm, 350 nm-400 nm,400 nm-450 nm, 450 nm-500 nm, 500 nm-550 nm, 550 nm-600 nm, 600 nm-650nm, 650 nm-700 nm, 700 nm-750 nm, 750 nm-800 nm, and 800 nm-1200 nm. Thelight sources may be chosen to match the spectral qualities of red,green and blue such that collectively when used in a light emittingdevice used as a display, the color gamut area is at least one selectedfrom the group: 70% NTSC, 80% NTSC, 90% NTSC, 100% NTSC, and 60%, 70%,80%, 90%, and 95% of the visible CIE u′ v′ color gamut of a standardviewer. In one embodiment, at least one light source is a white LEDpackage comprising a red, green, and blue LED.

In another embodiment, at least two light sources with different colorsare disposed to couple light into the lightguide through at least onelight input coupler. In another embodiment, a light emitting devicecomprises at least three light input couplers, at least three lightsources with different colors (red, green and blue for example) and atleast three lightguides. In another embodiment, a light source furthercomprises at least one selected from the group: reflective optic,reflector, reflector cup, collimator, primary optic, secondary optic,collimating lens, compound parabolic collimator, lens, reflectiveregion, and input coupling optic. The light source may also comprise anoptical path folding optic such as a curved reflector that can enablethe light source (and possibly heat-sink) to be oriented along adifferent edge of the light emitting device. The light source may alsocomprise a photonic bandgap structure, nano-structure or otherthree-dimensional arrangement that provides light output with an angularFWHM less than one selected from the group: 120 degrees, 100 degrees, 80degrees, 60 degrees, 40 degrees, and 20 degrees.

In another embodiment, a light emitting device comprises a light sourceemitting light in an angular full-width at half maximum intensity ofless than one selected from 150 degrees, 120 degrees, 100 degrees, 80degrees, 70 degrees, 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20degrees, and 10 degrees. In another embodiment, the light source furthercomprises at least one selected from the group: primary optic, secondaryoptic, and photonic bandgap region, and the angular full-width at halfmaximum intensity of the light source is less than one selected from 150degrees, 120 degrees, 100 degrees, 80 degrees, 70 degrees, 60 degrees,50 degrees, 40 degrees, 30 degrees, 20 degrees, and 10 degrees.

LED Array

In one embodiment, the light emitting device comprises a plurality ofLEDs or LED packages wherein the plurality of LEDs or LED packagescomprises an array of LEDs. The array components (LEDs or electricalcomponents) may be physically (and/or electrically) coupled to a singlecircuit board or they may be coupled to a plurality of circuit boardsthat may or may not be directly physically coupled (i.e. such as not onthe same circuit board). In one embodiment, the array of LEDs is anarray comprising at least two selected from the group: red, green, blue,and white LEDs. In this embodiment, the variation in the white point dueto manufacturing or component variations can be reduced. In anotherembodiment, the LED array comprises at least one cool white LED and onered LED. In this embodiment, the CRI, or Color Rendering Index, ishigher than the cool white LED illumination alone. In one embodiment,the CRI of at least one selected from the group: a light emittingregion, the light emitting surface, light fixture, light emittingdevice, display driven in a white mode comprising the light emittingdevice, and sign is greater than one selected from the group: 70, 75,80, 85, 90, 95, and 99. In another embodiment, the NIST Color QualityScale (CQS) of at least one selected from the group: a light emittingregion, the light emitting surface, light fixture, light emittingdevice, display driven in a white mode comprising the light emittingdevice, or sign is greater than one selected from the group: 70, 75, 80,85, 90, 95, and 99. In another embodiment, a display comprising thelight emitting device has a color gamut greater than 70%, 80%, 85%, 90%,95%, 100%, 105%, 110%, 120%, and 130% that of the NTSC standard. Inanother embodiment, the LED array comprises white, green, and red LEDs.In another embodiment, the LED array comprises at least one green andblue LED and two types of red LEDs with one type having a lower luminousefficacy or a lower wavelength than the other type of red LED. As usedherein, the white LED may be a phosphor converted blue LED or a phosphorconverted UV LED.

In another embodiment, the input array of LEDs can be arranged tocompensate for uneven absorption of light through longer verses shorterlightguides. In another embodiment, the absorption is compensated for bydirecting more light into the light input coupler corresponding to thelonger coupling lightguides or longer lightguides. In anotherembodiment, light within a first wavelength band is absorbed within thelightguide more than light within a second wavelength band and a firstratio of the radiant light flux coupled into the light input couplerwithin the first wavelength band divided by the radiant light fluxcoupled into the light input coupler within the second wavelength bandis greater than a second ratio of the radiant light flux emitted fromthe light emitting region within the first wavelength band divided bythe radiant light flux emitted from the light emitting region within thesecond wavelength band.

LED Array Location

In one embodiment, a plurality of LED arrays are disposed to couplelight into a single light input coupler or more than one light inputcoupler. In a further embodiment, a plurality of LEDs disposed on acircuit board are disposed to couple light into a plurality of lightinput couplers that direct light toward a plurality of sides of a lightemitting device comprising a light emitting region. In a furtherembodiment, a light emitting device comprises an LED array and lightinput coupler folded behind the light emitting region of the lightemitting device such that the LED array and light input coupler are notvisible when viewing the center of the light emitting region at an angleperpendicular to the surface. In another embodiment, a light emittingdevice comprises a single LED array disposed to couple light into atleast one light input coupler disposed to direct light into the lightemitting region from the bottom region of a light emitting device. Inone embodiment, a light emitting device comprises a first LED array anda second LED array disposed to couple light into a first light inputcoupler and a second light input coupler, respectively, wherein thefirst light input coupler and second light input coupler are disposed todirect light into the light emitting region from the top region andbottom region, respectively, of a light emitting device. In a furtherembodiment, a light emitting device comprises a first LED array, asecond LED array, and a third LED array, disposed to couple light into afirst light input coupler, a second light input coupler, and a thirdlight input coupler, respectively, disposed to direct light into thelight emitting region from the bottom region, left region, and rightregion, respectively, of a light emitting device. In another embodiment,a light emitting device comprises a first LED array, a second LED array,a third LED array, and a fourth LED array, disposed to couple light intoa first light input coupler, a second light input coupler, a third lightinput coupler, and a fourth light input coupler, respectively, disposedto direct light into the light emitting region from the bottom region,left region, right region, and top region, respectively, of a lightemitting device.

Wavelength Conversion Material

In another embodiment, the LED is a blue or ultraviolet LED combinedwith a phosphor. In another embodiment, a light emitting devicecomprises a light source with a first activating energy and a wavelengthconversion material which converts a first portion of the firstactivating energy into a second wavelength different than the first. Inanother embodiment, the light emitting device comprises at least onewavelength conversion material selected from the group: a fluorophore,phosphor, a fluorescent dye, an inorganic phosphor, photonic bandgapmaterial, a quantum dot material, a fluorescent protein, a fusionprotein, a fluorophores attached to protein to specific functionalgroups (such as amino groups (active ester, carboxylate, isothiocyanate,hydrazine), carboxyl groups (carbodiimide), thiol (maleimide, acetylbromide), azide (via click chemistry or non-specifically(glutaraldehyde))), quantum dot fluorophores, small moleculefluorophores, aromatic fluorophores, conjugated fluorophores, afluorescent dye, and other wavelength conversion material.

In one embodiment, the light source comprises a semiconductor lightemitter such as an LED and a wavelength conversion material thatconverts a portion of the light from the emitter to a shorter or longerwavelength. In another embodiment, at least one selected from the group:light input coupler, cladding region, coupling lightguide, input surfaceoptic, coupling optic, light mixing region, lightguide, light extractionfeature or region, and light emitting surface comprises a wavelengthconversion material.

Light Input Coupler Input Surface

In one embodiment, the light input coupler comprises a collection ofcoupling lightguides with a plurality of edges forming a light couplerinput surface. In another embodiment, an optical element is disposedbetween the light source and at least one coupling lightguide whereinthe optical element receives light from the light source through a lightcoupler input surface. In some embodiments, the input surface issubstantially polished, flat, or optically smooth such that light doesnot scatter forwards or backwards from pits, protrusions or other roughsurface features. In some embodiments, an optical element is disposed tobetween the light source and at least one coupling lightguide to providelight redirection as an input surface (when optically coupled to atleast one coupling lightguide) or as an optical element separate oroptically coupled to at least one coupling lightguide such that morelight is redirected into the lightguide at angles greater than thecritical angle within the lightguide than would be the case without theoptical element or with a flat input surface. In another embodiment, theinput surface is curved to refract more light received from the lightsource into angles within the lightguide greater than the critical anglewithin the lightguide than would occur with a flat input surface. Inanother embodiment, the optical element comprises radial or linearFresnel lens features which refract incident light. In anotherembodiment, the optical element comprises a refractive-TIR hybridFresnel lens (such as one having a low F/# of less than 1.5). In afurther embodiment, the optical element is a reflective and refractiveoptical element. In one embodiment, the light input surface may beformed by machine, cutting, polishing, forming, molding, or otherwiseremoving or adding material to the lightguide couplers to create asmooth, curved, rounded, concave, convex, rigged, grooved,micro-structured, nano-structured, or predetermined surface shape. Inanother embodiment, the light input coupler comprises an optical elementdesigned to collect light from the light source and increase theuniformity. Such optical elements can include fly's eye lenses,microlens arrays, integral lenses, lenticular lenses holographic orother diffusing elements with micro-scale features or nano-scalefeatures independent of how they were formed. In another embodiment, thelight input coupler is optically coupled to at least one lightguide andat least one light source. In another embodiment, the optical element isat least one selected from the group: diffractive element, holographicelement, lenticular element, lens, planar window, refractive element,reflective element, waveguide coupling element, anti-reflection coatedelement, planar element, and formed portion or region of at least oneselected from the group: coupling lightguide, optical adhesive, UV curedadhesive, and pressure sensitive adhesive. The light coupler or anelement therein may be comprised of at least one light transmittingmaterial. In another embodiment, an element of the light input coupleror the light input window, lens or surface is a silicone materialwherein the ASTM D1003 luminous transmittance change due to exposure to150 degrees centigrade for 200 hours is less than one selected from thegroup: 0.5%, 1%, 2%, 3%, 4%, and 5%. In another embodiment, the inputsurface of the coupling lightguides, the coupling lightguides, or thewindow optically coupled to the input surface is optically coupled usinga light transmitting optical adhesive to one or more selected from thegroup: an optical window, a light source, the outer surface of an LED, alight collimating optical element, a light redirecting optical element,a light turning optical element, an intermediate lens, or a lighttransmitting optical element.

When light propagating in air is incident to a planar light inputsurface of a light transmitting material with a refractive index higherthan 1.3 at high angles from the normal to the interface, for example,much of the light is reflected from the air-input surface interface. Onemethod of reducing the loss of light due to reflection is to opticallycouple the input surface of the light input coupler to the light source.Another method to reduce this loss is to use a collimation optic oroptic that directs some of the light output from the light source intoangles closer to the optical axis of the light source. The collimatingoptic, or optical element, may be optically coupled to the light source,the coupling lightguides, an adhesive, or other optical element suchthat it directs more light into the coupling lightguides into a totalinternal reflection condition within the coupling lightguides. Inanother embodiment, the light input surface comprises a recessed cavityor concave region such that the percentage of light from a light sourcedisposed adjacent to the cavity or concave region that is reflected fromthe input surface is less than one selected from the group: 40%, 30%,20%, 10%, 5%, 3%, and 2%.

In another embodiment, the total input area ratio, defined as the totalarea of the input surface of all of the light input couplers of thelight emitting device receiving more than 5% of the total light fluxfrom any light source divided by the total light emitting surface areasof the light sources is greater than one selected from the group: 0.9,1, 1.5, 2, 4, and 5. In another embodiment, the individual input arearatio, defined as the area of the input surface of a light input couplerof the light emitting device receiving more than 5% of the total lightflux received from a light source divided by the light emitting surfacearea of the light source is greater than one selected from the group:0.9, 1, 1.5, 2, 4, and 5. The individual input area ratios of a lightemitting device may vary for different input couplers and the individualinput area ratio for a particular input coupler may be greater or lessthan the total input area ratio.

Input Surface Position Relative to Light Source

In one embodiment, the distance between the outer surface of the lightsource and the input surface of the light input coupler is less than oneselected from the group: 3 millimeters, 2 millimeters, 1 millimeter, 0.5millimeters, and 0.25 millimeters over a time period between just beforepowering on the light source and the time for a substantiallysteady-state junction temperature of the light source at a maintainedambient temperature for the light emitting device of 20 degrees Celsius.

In one embodiment, an elastic object used to store mechanical energy isdisposed to force the outer surface of the light source to be in contactor a predetermined distance from the input surface of the light inputcoupler. In one embodiment, the elastic object is one selected from thegroup: tension spring, extension spring, compression spring, torsionspring, wire spring, coiled spring, flat spring, cantilever spring, coilspring, helical spring, conical spring, compression spring, volutespring, hairspring, balance spring, leaf spring, V-spring, Bellevillewasher, Belleville spring, constant-force spring, gas spring,mainspring, rubber band, spring washer, a torsion bar twisted underload, torsion spring, negator spring, and wave spring. In oneembodiment, the elastic object is disposed between the light source orLED array and the housing or other element such as a thermal transferelement such that a force is exerted against the light source or LEDarray such that the relative distance between the outer light emittingsurface of the light source or LED array and the input surface of thelight input coupler remains within 0.5 millimeters of a fixed distanceover a time period between just before powering on the light source andthe time for a substantially steady-state junction temperature of thelight source at a maintained ambient temperature for the light emittingdevice of 20 degrees Celsius.

In a further embodiment, a spacer comprises a physical element thatsubstantially maintains the minimum separation distance of at least onelight source and at least one input surface of at least one light inputcoupler. In one embodiment, the spacer is one selected from the group: acomponent of the light source, a region of a film (such as a whitereflective film or low contact area cover film), a component of an LEDarray (such as a plastic protrusion), a component of the housing, acomponent of a thermal transfer element, a component of the holder, acomponent of the relative position maintaining element, a component ofthe light input surface, a component physically coupled to the lightinput coupler, light input surface, at least one coupling lightguide,window for the coupling lightguide, lightguide, housing or othercomponent of the light emitting device.

In a further embodiment, at least one selected from the group: the film,lightguide, light mixing region, light input coupler, and couplinglightguide comprises a relative position maintaining mechanism thatmaintains the relative distance between the outer light emitting surfaceof the light source or LED array and the input surface of the lightinput coupler remains within 0.5 millimeters of a fixed distance over atime period between just before powering on the light source and thetime for a substantially steady-state junction temperature of the lightsource at a maintained ambient temperature for the light emitting deviceof 20 degrees Celsius. In one embodiment, the relative positionmaintaining mechanism is a hole in the lightguide and a pin in acomponent (such as a thermal transfer element) physically coupled to thelight source. For example, pins in a thin aluminum sheet thermaltransfer element physically coupled to the light source are registeredinto holes within the light input coupler (or a component of the lightinput coupler such as a coupling lightguide) to maintain the distancebetween the input surface of the light input coupler and the lightemitting surface of the light source. In another embodiment, therelative position maintaining mechanism is a guide device.

Stacked Strips or Segments of Film Forming a Light Input Coupler

In one embodiment, the light input coupler is region of a film thatcomprises the lightguide and the light input coupler which comprisesstrip sections of the film which form coupling lightguides that aregrouped together to form a light coupler input surface. The couplinglightguides may be grouped together such the edges opposite thelightguide region are brought together to form an input surfacecomprising of their thin edges. A planar input surface for a light inputcoupler can provide beneficial refraction to redirect a portion of theinput light from the surface into angles such that it propagates atangles greater than the critical angle for the lightguide. In anotherembodiment, a substantially planar light transmitting element isoptically coupled to the grouped edges of coupling lightguides. One ormore of the edges of the coupling lightguides may be polished, melted,adhered with an optical adhesive, solvent welded, or otherwise opticallycoupled along a region of the edge surface such that the surface issubstantially polished, smooth, flat, or substantially planarized. Thispolishing can aide to reduce light scattering, reflecting, or refractioninto angles less than the critical angle within the coupling lightguidesor backwards toward the light source. The light input surface maycomprise a surface of the optical element, the surface of an adhesive,the surface of more than one optical element, the surface of the edge ofone or more coupling lightguides, or a combination of one or more of theaforementioned surfaces. The light input coupler may also comprise anoptical element that has an opening or window wherein a portion of lightfrom a light source may directly pass into the coupling lightguideswithout passing through the optical element. The light input coupler oran element or region therein may also comprise a cladding material orregion.

In another embodiment, the cladding layer is formed in a materialwherein under at least one selected from the group: heat, pressure,solvent, and electromagnetic radiation, a portion of the cladding layermay be removed. In one embodiment, the cladding layer has a glasstransition temperature less than the core region and pressure applied tothe coupling lightguides near the light input edges reduces the totalthickness of the cladding to less than one selected from the group: 10%,20%, 40%, 60%, 80% and 90% of the thickness of the cladding regionsbefore the pressure is applied. In another embodiment, the claddinglayer has a glass transition temperature less than the core region andheat and pressure applied to the coupling lightguides near the lightinput edges reduces the total thickness of the cladding regions to lessthan one selected from the group: 10%, 20%, 40%, 60%, 80% and 90% of thethickness of the cladding regions before the heat and pressure isapplied. In another embodiment, a pressure sensitive adhesives functionsas a cladding layer and the coupling lightguides are folded such thatthe pressure sensitive adhesive or component on one or both sides of thecoupling lightguides holds the coupling lightguides together and atleast 10% of the thickness of the pressure sensitive adhesive is removedfrom the light input surface by applying heat and pressure.

Guide Device for Coupling the Light Source to the Light Input Surface ofthe Light Input Coupler

The light input coupler may also comprise a guide that comprises amechanical, electrical, manual, guided, or other system or component tofacility the alignment of the light source in relation to the lightinput surface. The guide device may comprise an opening or window andmay physically or optically couple together one or more selected fromthe group: light source (or component physically attached to a lightsource), a light input coupler, coupling lightguide, housing, andelectrical, thermal, or mechanical element of the light emitting device.In one embodiment of this device an optical element comprises one ormore guides disposed to physically couple or align the light source(such as an LED strip) to the optical element or coupling lightguides.In another embodiment, the optical element comprises one or more guideregions disposed to physically couple or align the optical element tothe light input surface of the input coupler. The guide may comprise agroove and ridge, hole and pin, male and corresponding female component,or a fastener. In one embodiment, the guide comprises a fastenerselected from the group: a batten, button, clamp, clasp, clip, clutch(pin fastener), flange, grommet, anchor, nail, pin, peg, clevis pin,cotter pin, linchpin, R-clip, retaining ring, circlip retaining ring,e-ring retaining ring, rivet, screw anchor, snap, staple, stitch, strap,tack, threaded fastener, captive threaded fasteners (nut, screw, stud,threaded insert, threaded rod), tie, toggle, hook-and-loop strips, wedgeanchor, and zipper. In another embodiment, one or more guide regions aredisposed to physically couple or align one or more films, film segments(such as coupling lightguides), thermal transfer elements, housing orother components of the light emitting device together.

Light Redirecting Optical Element

In one embodiment, a light redirecting optical element is disposed toreceive light from at least one light source and redirect the light intoa plurality of coupling lightguides. In another embodiment, the lightredirecting optical element is at least one selected from the group:secondary optic, mirrored element or surface, reflective film such asaluminized PET, giant birefringent optical films such as Vikuiti™Enhanced Specular Reflector Film by 3M Inc., curved mirror, totallyinternally reflecting element, beamsplitter, and dichroic reflectingmirror or film.

In another embodiment, a first portion of light from a light source witha first wavelength spectrum is directed by reflection by a wavelengthselective reflecting element (such as a dichroic filter) into aplurality of coupling lightguides. In another embodiment, a firstportion of light from a light source with a first wavelength spectrum isdirected by reflection by a wavelength selective reflecting element(such as a dichroic filter) into a plurality of coupling lightguides anda second portion of light from a second light source with a secondwavelength spectrum is transmitted through the wavelength selectivereflecting element into the plurality of coupling lightguides. Forexample, in one embodiment, a red light from an LED emitting red lightis reflected by a first dichroic filter oriented at 45 degrees andreflects light into a set of coupling lightguides. Green light from anLED emitting green light is reflected by a second dichroic filteroriented at 45 degrees and passes through the first dichroic filter intothe set of coupling lightguides. Blue light from a blue LED is directedtoward and passes through the first and second dichroic filters into thecoupling lightguides. Other combinations of light coupling or combiningthe output from multiple light sources into an input surface or apertureare known in the field of projection engine design and include methodsfor combining light output from color LEDs onto an aperture such as amicrodisplay. These techniques may be readily adapted to embodimentswherein the microdisplay or spatial light modulator is replaced by theinput surface of coupling lightguides.

Light Collimating Optical Element

In one embodiment, the light input coupler comprises a light collimatingoptical element. A light collimating optical element receives light fromthe light source with a first angular full-width at half maximumintensity within at least one input plane orthogonal to the inputsurface and redirects a portion of the incident light from the lightsource such that the angular full-width at half maximum intensity of thelight is reduced in the first input plane. In one embodiment, the lightcollimating optical element is one or more of the following: a lightsource primary optic, a light source secondary optic, a light inputsurface, and an optical element disposed between the light source and atleast one coupling lightguide. In another embodiment, the lightcollimating element is one or more of the following: an injection moldedoptical lens, a thermoformed optical lens, and a cross-linked lens madefrom a mold. In another embodiment, the light collimating elementreduces the angular full-width at half maximum (FWHM) intensity within afirst input plane and a second plane orthogonal to the first inputplane.

Light Turning Optical Element

In one embodiment, a light input coupler comprises a light turningoptical element disposed to receive light from a light source with afirst optical axis angle and redirect the light to having a secondoptical axis angle different than the first optical axis angle. In oneembodiment, the light turning optical element redirects light by about90 degrees. In another embodiment, the light turning optical elementredirects the optical axis of the incident light by an angle selectedfrom within the range of 75 degrees and 90 degrees within at least oneplane. In another embodiment, the light turning optical elementredirects the optical axis of the incident light by an angle selectedfrom within the range of 40 degrees and 140 degrees. In one embodiment,the light turning optical element is optically coupled to the lightsource or the light input surface of the coupling lightguides. Inanother embodiment, the light turning optical element is separated inthe optical path of light from the light source or the light inputsurface of the coupling lightguides by an air gap. In anotherembodiment, the light turning optical element redirects light from twoor more light sources with first optical axis angles to light havingsecond optical axis angles different than the first optical axis angles.In a further embodiment, the light turning optical element redirects afirst portion of light from a light source with a first optical axisangle to light having a second optical axis angle different than thefirst optical axis angle. In another embodiment, the light turningoptical element redirects light from a first light source with a firstoptical axis angle to light having a second optical axis angle differentfrom the first optical axis angle and light from a second light sourcewith a third optical axis angle to light having a fourth optical axisangle different from the third optical axis angle.

Bi-Directional Light Turning Optical Element

In another embodiment, the light turning optical element redirects theoptical axis of light from one or more light sources into two differentdirections. For example, in one embodiment, the middle couplinglightguide of a light input coupler is a non-folded coupling lightguideand the light input ends of two arrays of stacked, folded couplinglightguides are directed toward the middle coupling lightguide. Abi-directional light turning optical element is disposed above themiddle coupling lightguide such that a first portion of light from alight source enters the middle coupling lightguide, a second portion oflight from the light source is directed in a first direction paralleland toward the input surface of the first stacked array of foldedcoupling lightguides by the bi-directional light turning opticalelement, and a third portion of light from the light source is directedin a second direction parallel and toward the input surface of thesecond stacked array of folded coupling lightguides by thebi-directional light turning optical element. In this embodiment, thelight source may be disposed between the lateral edges of the lightemitting region or light emitting device and the non-folded couplinglightguide eliminates an otherwise dark region (where there isinsufficient room for a folded coupling lightguide) or eliminates therequirement for multiple bends in the coupling lightguides that canintroduce further light loss and increase volume requirements.

In one embodiment, the bi-directional light turning optical elementsplits and turns the optical axis of one light source into two differentdirections. In another embodiment, the bi-directional light turningoptical element rotates the optical axis of a first light source into afirst direction and rotates the optical axis of a second light sourceinto a second direction different that the first direction. In anotherembodiment, an optical element, such as an injection molded lens,comprises more than one light turning optical element and lightcollimating element that are configured to receive light from more thanone light source. For example, an injection molded lens comprising alinear array of optical light turning surfaces and light collimatingsurfaces may be disposed to receive light from a strip comprising alinear array of LEDs such that the light is directed into a plurality oflight input couplers or stacks of coupling lightguides. By forming asingle optical element to perform light turning and light collimatingfor a plurality of light sources, fewer optical elements are needed andcosts can be reduced. In another embodiment, the bi-directional lightturning element may be optically coupled to the light source, thecoupling lightguides, or a combination thereof.

Light Turning and Light Collimating Optical Element

In another embodiment, the light turning optical element turns theoptical axis of the light from the light source in a first plane withinthe light turning element and collimates the light in the first plane,in a second plane orthogonal to the first plane, or a combinationthereof. In another embodiment, the light turning optical elementcomprises a light turning region and a collimating region. In oneembodiment, by collimating input light in at least one plane, the lightwill propagate more efficiently within the lightguide and have reducedlosses in the bend regions and reduced input coupling losses into thecoupling lightguides. In one embodiment, the light turning opticalelement is an injection molded lens designed to redirect light from afirst optical axis angle to a second optical axis angle different fromthe first optical axis angle. The injection molded lens may be formed ofa light transmitting material such as poly(methyl methacrylate) (PMMA),polycarbonate, silicone, or any suitable light transmitting material. Ina further embodiment, the light turning element may be a substantiallyplanar element that redirects light from a first optical axis angle to asecond optical axis angle in a first plane while substantiallymaintaining the optical axis angle in a second plane orthogonal to thefirst plane. For example, in one embodiment, the light turning opticalelement is a 1 millimeter (mm) thick lens with a curved profile in oneplane cut from a 1 mm sheet of PMMA using a carbon dioxide (CO₂) lasercutter.

In one embodiment, the light input coupler comprises a light turningoptical element or coupling lightguides with light turning edges thatpermit a light source to be disposed between the extended boundingregions of the sides of the light emitting surface adjacent to the inputside of the light from the light source into the lightguide region. Inthis embodiment, the turning optical element or light turning edgespermit the light source to be disposed on the light input side region ofthe lightguide region without substantially extending beyond eitherside. Additionally, in this embodiment, the light source may be foldedbehind the light emitting region of the lightguide such that the lightsource does not substantially extend beyond an edge of the lightemitting region or outer surface of the light emitting device comprisingthe light emitting region. In another embodiment, the light source issubstantially directed with its optical axis oriented toward the lightemitting region and the turning optical element or turning edges of thecoupling lightguides permit the light to be turned such that it canenter the stacked array of coupling lightguides that are stackedsubstantially parallel to the input side of the lightguide region andsubstantially orthogonal to the light source optical axis.

Light Coupling Optical Element

In one embodiment, a light emitting device comprises a light couplingoptical element disposed to receive light from the light source andtransmit a larger flux of light into the coupling lightguides than wouldoccur without the light coupling element. In one embodiment, the lightcoupling element refracts a first portion of incident light from a lightsource such that it is incident upon the input surface of one or morecoupling lightguides or sets of coupling lightguides at a lowerincidence angle from the normal such that more light flux is coupledinto the coupling lightguides or sets of coupling lightguides (lesslight is lost due to reflection). In another embodiment, the lightcoupling optical element is optically coupled to at least one selectedfrom the group: the light source, a plurality of coupling lightguides, aplurality of sets of coupling lightguides, a plurality of light sources.

Thermal Stability of Optical Element

In another embodiment, the light coupling optical element or lightredirecting optical element contains materials with a volumetric averageglass transition temperature higher than the volumetric average glasstransition temperature of the materials contained within the couplinglightguides. In another embodiment, the glass transition temperature ofthe coupling lightguides is less than 100 degrees Centigrade and theglass transition temperature of the light coupling optical element orthe light redirecting optical element is greater than 100 degreesCentigrade. In a further embodiment, the glass transition temperature ofthe coupling lightguides is less than 120 degrees Centigrade and theglass transition temperature of the light coupling optical element orthe light redirecting optical element is greater than 120 degreesCentigrade. In a further embodiment, the glass transition temperature ofthe coupling lightguides is less than 140 degrees Centigrade and theglass transition temperature of the light coupling optical element orthe light redirecting optical element is greater than 140 degreesCentigrade. In a further embodiment, the glass transition temperature ofthe coupling lightguides is less than 150 degrees Centigrade and theglass transition temperature of the light coupling optical element orthe light redirecting optical element is greater than 150 degreesCentigrade. In another embodiment, the light redirecting optical elementor the light coupling optical element comprises polycarbonate and thecoupling lightguides comprise poly(methyl methacrylate). In anotherembodiment, at least one of the light redirecting optical element andthe light coupling optical element is thermally coupled to a thermaltransfer element or the housing of the light emitting device.

Coupling Lightguides

In one embodiment, the coupling lightguide is a region wherein lightwithin the region can propagate in a waveguide condition and a portionof the light input into a surface or region of the coupling lightguidespasses through the coupling lightguide toward a lightguide or lightmixing region. The coupling lightguide, in some embodiments, may serveto geometrically transform a portion of the flux from a light sourcefrom a first shaped area to a second shaped area different from thefirst. In an example of this embodiment, the light input surface of thelight input coupler formed from the edges of folded strips (couplinglightguides) of a planar film has the dimensions of a rectangle that is3 millimeters by 2.7 millimeters and the light input coupler coupleslight into a planar section of a film in the light mixing region withcross-sectional dimensions of 40.5 millimeters by 0.2 millimeters. Inone embodiment, the input area of the light input coupler issubstantially the same as the cross-sectional area of the light mixingregion or lightguide disposed to receive light from one or more couplinglightguides. In another embodiment, the total transformation ratio,defined as the total light input surface area of the light inputcouplers receiving more than 5% of the light flux from a light sourcedivided by the total cross-sectional area of the light mixing region orlightguide region disposed to receive light from the couplinglightguides is one selected from the group: 1 to 1.1, 0.9 to 1, 0.8 to0.9, 0.7 to 0.8, 0.6 to 0.7, 0.5 to 0.6, 0.5 to 0.999, 0.6 to 0.999, 0.7to 0.999, less than 1, greater than 1, equal to 1. In anotherembodiment, the input surface area of each light input couplercorresponding to the edges of coupling lightguides disposed to receivelight from a light source is substantially the same as thecross-sectional area of the light mixing region or lightguide regiondisposed to receive light from each corresponding coupling lightguides.In another embodiment, the individual transformation ratio, defined asthe total light input area of a single light input surface of a lightinput coupler (corresponding to the edges of coupling lightguides)divided by the total cross-sectional area of the light mixing region orlightguide disposed to receive light from the corresponding couplinglightguides is one selected from the group: 1 to 1.1, 0.9 to 1, 0.8 to0.9, 0.7 to 0.8, 0.6 to 0.7, 0.5 to 0.6, 0.5 to 0.999, 0.6 to 0.999, 0.7to 0.999, less than 1, greater than 1, equal to 1.

In another embodiment, a coupling lightguide is disposed to receivelight from at least one input surface with a first input surface longestdimension and transmit the light to a lightguide with a light emittingsurface with a light emitting surface longest dimension larger than thefirst input surface largest dimension. In another embodiment, thecoupling lightguide is a plurality of lightguides disposed to collectlight from at least one light source through edges or surfaces of thecoupling lightguides and direct the light into the surface, edge, orregion of a lightguide comprising a light emitting surface. In oneembodiment, the coupling lightguides provide light channels wherebylight flux entering the coupling lightguides in a first cross-sectionalarea can be redistributed into a second cross sectional area differentfrom the first cross sectional area at the light output region of thelight input coupler. The light exiting the light input coupler or lightmixing region may then propagate to a lightguide or lightguide regionwhich may be a separate region of the same element (such as a separateregion of the same film). In one embodiment, a light emitting devicecomprises a light source and a film processed to form a lightguideregion with light extraction features, a light mixing region whereinlight from a plurality of sources, light input couplers, or couplinglightguides mixes before entering into the lightguide region. Thecoupling lightguides, light mixing region, and light extraction featuresmay all be formed from, on, or within the same film and they may remaininterconnected to each other through one or more regions.

In one embodiment, at least one coupling lightguide is disposed toreceive light from a plurality of light sources of at least twodifferent colors, wherein the light received by the coupling lightguideis pre-mixed angularly, spatially, or both by reflecting through thecoupling lightguide and the 9-spot sampled spatial color non-uniformity,Δu′v′, of the light emitting surface of the light emitting devicemeasured on the 1976 u′, v′ Uniform Chromaticity Scale as described inVESA Flat Panel Display Measurements Standard version 2.0, Jun. 1, 2001(Appendix 201, page 249) is less than one selected from the group: 0.2,0.1, 0.05, 0.01, and 0.004 when measured using a spectrometer based spotcolor meter.

Coupling Lightguide Folds and Bends

In one embodiment, light emitting device comprises a light mixing regiondisposed between a lightguide and strips or segments cut to formcoupling lightguides, whereby a collection of edges of the strips orsegments are brought together to form a light input surface of the lightinput coupler disposed to receive light from a light source. In oneembodiment, the light input coupler comprises a coupling lightguidewherein the coupling lightguide comprises at least one fold or bend inone plane such that at least one edge overlaps another edge. In anotherembodiment, the coupling lightguide comprises a plurality of folds orbends wherein edges of the coupling lightguide can be abutted togetherin region such that the region forms a light input surface of the lightinput coupler of the light emitting device.

In one embodiment, a light emitting device comprises a light inputcoupler comprising at least one coupling lightguide that is bent orfolded such that light propagating in a first direction within thelightguide before the bend or fold is propagating in a second directiondifferent that the first within the lightguide after the bend or fold.

In one embodiment, at least one coupling lightguide comprises a strip orsegment that is bent or folded to radius of curvature of less than 75times the thickness of the strip or segment. In another embodiment, atleast one coupling lightguide comprises a strip or segment that isbended or folded to radius of curvature greater than 10 times the timesthe thickness of the strip or segment. In another embodiment, at leastone coupling lightguide is bent or folded such that longest dimension ina cross-section through the light emitting device or coupling lightguidein at least one plane is less than without the fold or bend. Segments orstrips may be bent or folded in more than one direction or region andthe directions of folding or bending may be different between strips orsegments.

Optical Efficiency of the Light Input Coupler

In an embodiment, the optical efficiency of the light input coupler,defined as the percentage of the original light flux from the lightsource that passes through the light input coupler light input surfaceand out of the light input coupler into a mixing region, lightguide, orlight emitting surface, is greater than one selected from the group:50%, 60%, 70%, 80%, 90%, and 95%. The degree of collimation can affectthe optical efficiency of the light input coupler.

Collimation of Light Entering the Coupling Lightguides

In one embodiment, at least one selected from the group: light source,light collimating optical element, light source primary optic, lightsource secondary optic, light input surface, optical element disposedbetween the light source and at least one selected from the group:coupling lightguide, shape of the coupling lightguide, shape of themixing region, shape of the light input coupler, and shape of an elementor region of the light input coupler provides light incident to thelight input surface or within the coupling lightguide with an angularfull-width of half maximum intensity chosen from the group: less than 80degrees, less than 70 degrees, less than 60 degrees, less than 50degrees, less than 40 degrees, less than 30 degrees, less than 20degrees, less than 10 degrees, between 10 degrees and 30 degrees,between 30 degrees and 50 degrees, between 10 degrees and 60 degrees andbetween 30 degrees and 80 degrees within a first plane orthogonal to theinput surface. In some embodiments, light which is highly collimated(FWHM of about 10 degrees or less) does not mix spatially within alightguide region with light extracting features such that there may bedark bands or regions of non-uniformity. In this embodiment, the light,however, will be efficiently coupled around curves and bends in thelightguide relative to less collimated light and in some embodiments,the high degree of collimation enables small radii of curvature and thusa smaller volume for the fold or bend in a light input coupler andresulting light emitting device. In another embodiment, a significantportion of light from a light source with a low degree of collimation(FWHM of about 120 degrees) within the coupling lightguides will bereflected into angles such that it exits the coupling lightguides inregions near bends or folds with small radii of curvature. In thisembodiment, the spatial light mixing (providing uniform color orluminance) of the light from the coupling lightguides in the lightguidein areas of the light extracting regions is high and the light extractedfrom lightguide will appear to have a more uniform angular or spatialcolor or luminance uniformity.

In one embodiment, light from a light source is collimated in a firstplane by a light collimating optical element and the light is collimatedin a second plane orthogonal to the first plane by light collimatingedges of the coupling lightguide. In another embodiment, a first portionof light from a light source is collimated by a light collimatingelement in a first plane and the first portion of light is furthercollimated in a second plane orthogonal to the first plane, the firstplane, or a combination thereof by collimating edges of one or morecoupling lightguides. In a further embodiment, a first portion of lightfrom a light source is collimated by a light collimating element in afirst plane and a second portion of light from the light source or firstportion of light is collimated in a second plane orthogonal to the firstplane, the first plane, or a combination thereof by collimating edges ofone or more coupling lightguides.

In another embodiment, one or more coupling lightguides is bent orfolded and the optical axis of the light source is oriented at a firstredirection angle to the light emitting device optical axis, oriented ata second redirection angle to a second direction orthogonal to the lightemitting device optical axis, and oriented at a third redirection angleto a third direction orthogonal to the light emitting device opticalaxis and the second direction. In another embodiment, the firstredirection angle, second redirection angle, or third redirection angleis about one selected from the group: 0 degrees, 45 degrees, 90 degrees,135 degrees, 180 degrees, 0-90 degrees, 90-180 degrees, and 0-180degrees.

Each light source may be oriented at a different angle. For example, twolight sources along one edge of a film with a strip-type light inputcoupler can be oriented directly toward each other (the optical axes are180 degrees apart). In another example, the light sources can bedisposed in the center of an edge of a film and oriented away from eachother (the optical axes are also 180 degrees apart).

The segments or strips may be once folded, for example, with the stripsoriented and abutting each other along one side of a film such that thelight source optical axis is in a direction substantially parallel withthe film plane or lightguide plane. The strips or segments may also befolded twice, for example, such that the light source optical axis issubstantially normal to the film plane or normal to the waveguide.

In one embodiment, the fold or bend in the coupling lightguide, regionor segment of the coupling lightguide or the light input coupler has acrease or radial center of the bend in a direction that is at a bendangle relative to the light source optical axis. In another embodiment,the bend angle is one selected from the group: 0 degrees, 45 degrees, 90degrees, 135 degrees, 180 degrees, 0-90 degrees, 90-180 degrees, and0-180 degrees.

The bend or fold may also be of the single directional bend (such asvertical type, horizontal type, 45-degree type or other single angle) orthe bend or fold or be multi-directional such as the twisted typewherein the strip or segment is torsional. In one embodiment, the strip,segment or region of the coupling lightguide is simultaneously bent intwo directions such that the strip or segment is twisted.

In another embodiment, the light input coupler comprises at least onelight source disposed to input light into the edges of strips (orcoupling lightguides) cut into a film wherein the strips are twisted andaligned with their edges forming an input surface and the light sourceoutput surface area is substantially parallel with the edge of thecoupling lightguide, lightguide, lightguide region, or light inputsurface or the optical axis of the light source is substantiallyperpendicular to the edge of the coupling lightguide, lightguide,lightguide region, or light input surface. In another embodiment,multiple light sources are disposed to couple light into a light inputcoupler comprising strips cut into a film such that at least one lightsource has an optical axis substantially parallel to the lightguideedge, coupling lightguide lateral edge or the nearest edge of thelightguide region. In another embodiment, two groupings of couplinglightguides are folded separately toward each other such that theseparation between the ends of the strips is substantially the thicknessof the central strip between the two groupings and two or more lightsources are disposed to direct light in substantially oppositedirections into the strips. In one embodiment, two groupings of couplinglightguides are folded separately toward each other such and then bothfolded in a direction away from the film such that the edges of thecoupling lightguides are brought together to form a single light inputsurface disposed to receive light from at least one light source. Inthis embodiment, the optical axis of the light source may besubstantially normal to the substantially planar film-based lightguide.

In one embodiment, two opposing stacks of coupling lightguides from thesame film are folded and recombined at some point away from the end ofthe coupling apparatus. This can be accomplished by splitting the filminto one or more sets of two bundles, which are folded towards eachother. In this embodiment, the bundles can be folded at an additionaltight radius and recombined into a single stack. The stack input canfurther be polished to be a flat single input surface or opticallycoupled to a flat window and disposed to receive light from a lightsource.

In one embodiment, the combination of the two film stacks is configuredto reduce the overall volume. In one embodiment, the film is bent orfolded to a radius of curvature greater than 10× the film thicknessorder to retain sufficient total internal reflection for a first portionof the light propagating within the film.

In another embodiment, the light input coupler comprises at least onecoupling lightguide wherein the coupling lightguide comprises an arcuatereflective edge and is folded multiple times in a fold directionsubstantially parallel to the lightguide edge or nearest edge of thelightguide region wherein multiple folds are used to bring sections ofan edge together to form a light input surface with a smaller dimension.In another embodiment, the light coupling lightguide, the strips, orsegments have collimating sections cut from the coupling lightguidewhich directs light substantially more parallel to the optical axis ofthe light source. In one embodiment, the collimating sections of thecoupling lightguide, strips or segments direct light substantially moreparallel to the optical axis of the light source in at least one planesubstantially parallel to the lightguide or lightguide region.

In a further embodiment, a light input coupler comprises at least onecoupling lightguide with an arc, segmented arc, or other light redirectedge cut into a film and the light input coupler comprises a region ofthe film rolled up to form a spiral or concentric-circle-like lightinput edge disposed to receive light from a light source.

Coupling Lightguide Lateral Edges

In one embodiment, the lateral edges, defined herein as the edges of thecoupling lightguide which do not substantially receive light directlyfrom the light source and are not part of the edges of the lightguide.The lateral edges of the coupling lightguide receive light substantiallyonly from light propagating within the coupling light guide. In oneembodiment, the lateral edges are at least one selected from the group:of uncoated, coated with a reflecting material, disposed adjacent to areflecting material, and cut with a specific cross-sectional profile.The lateral edges may be coated, bonded to or disposed adjacent to aspecularly reflecting material, partially diffusely reflecting material,or diffuse reflecting material. In one embodiment, the edges are coatedwith a specularly reflecting ink comprising nano-sized or micron-sizedparticles or flakes which substantially reflect the light in a specularmanner when the coupling lightguides are brought together from foldingor bending. In another embodiment, a light reflecting element (such as amulti-layer mirror polymer film with high reflectivity) is disposed nearthe lateral edge of at least one region of a coupling lightguidedisposed, the multi-layer mirror polymer film with high reflectivity isdisposed to receive light from the edge and reflect it and direct itback into the lightguide. In another embodiment, the lateral edges arerounded and the percentage of incident light diffracted out of thelightguide from the edge is reduced. One method of achieving roundededges is by using a laser to cut the strips, segments or couplinglightguide region from a film and edge rounding through control of theprocessing parameters (speed of cut, frequency of cut, laser power,etc.). Other methods for creating rounded edges include mechanicalsanding/polishing or from chemical/vapor polishing. In anotherembodiment, the lateral edges of a region of a coupling lightguide aretapered, angled serrated, or otherwise cut or formed such that lightfrom a light source propagating within the coupling lightguide reflectsfrom the edge such that it is directed into an angle closer to theoptical axis of the light source, toward a folded or bent region, ortoward a lightguide or lightguide region.

Width of Coupling Lightguides

In one embodiment, the dimensions of the coupling lightguides aresubstantially equal in width and thickness to each other such that theinput surface areas for each edge surface are substantially the same. Inanother embodiment, the average width of the coupling lightguides, w, isdetermined by the equation:w=MF*W _(LES) /NC,

where W_(LES) is the total width of the light emitting surface in thedirection parallel to the light entrance edge of the lightguide regionor lightguide receiving light from the coupling lightguide, NC is thetotal number of coupling lightguides in the direction parallel to thelight entrance edge of the lightguide region or lightguide receivinglight from the coupling lightguide, and MF is the magnification factor.In one embodiment, the magnification factor is one selected from thegroup: 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 0.7-1.3, 0.8-1.2, and0.9-1.1. In another embodiment, at least one selected from the group:coupling lightguide width, the largest width of a coupling waveguide,the average width of the coupling lightguides, and the width of eachcoupling lightguides is selected from the group: 0.5 mm-1 mm, 1 mm-2 mm,2 mm-3 mm, 3 mm-4 mm, 5 mm-6 mm, 0.5 mm-2 mm, 0.5 mm-25 mm, 0.5 mm-10mm, 10-37 mm, and 0.5 mm-5 mm. In one embodiment, at least one selectedfrom the group: the coupling lightguide width, the largest width of acoupling waveguide, the average width of the coupling lightguides, andthe width of each coupling lightguides is less than 20 millimeters.

Shaped or Tapered Coupling Lightguides

The width of the coupling lightguides may vary in a predeterminedpattern. In one embodiment, the width of the coupling lightguides variesfrom a large width in a central coupling lightguide to smaller width inlightguides further from the central coupling lightguide as viewed whenthe light input edges of the coupling lightguides are disposed togetherto form a light input surface on the light input coupler. In thisembodiment, a light source with a substantially circular light outputaperture can couple into the coupling lightguides such that the light athigher angles from the optical axis are coupled into a smaller widthstrip such that the uniformity of the light emitting surface along theedge of the lightguide or lightguide region and parallel to the inputedge of the lightguide region disposed to receive the light from thecoupling lightguides is greater than one selected from the group: 60%,70%, 80%, 90% and 95%.

Other shapes of stacked coupling lightguides can be envisioned, such astriangular, square, rectangular, oval, etc. that provide matched inputareas to the light emitting surface of the light source. The widths ofthe coupling lightguides may also be tapered such that they redirect aportion of light received from the light source. The lightguides may betapered near the light source, in the area along the coupling lightguidebetween the light source and the lightguide region, near the lightguideregion, or some combination thereof.

In some embodiments, one light source will not provide sufficient lightflux to enable the desired luminance or light output profile desired fora particular light emitting device. In this example, one may use morethan one light input coupler and light source along the edge or side ofa lightguide region or lightguide mixing region. In one embodiment, theaverage width of the coupling lightguides for at least one light inputcoupler are in a first width range selected from the group: 1-3, 1.01-3,1.01-4, 0.7-1.5, 0.8-1.5, 0.9-1.5, 1-2, 1.1-2, 1.2-2, 1.3-2, 1.4-2,0.7-2, 0.5-2, and 0.5-3 times the largest width of the light outputsurface of the light source in the direction of the lightguide couplerwidth at the light input surface.

In one embodiment, the coupling lightguide dimensional ratio, the ratioof the width of the coupling lightguide (the width is measured as theaverage dimension orthogonal to the general direction of propagatingwithin the coupling lightguide toward the light mixing region,lightguide, or lightguide region) to the thickness of the couplinglightguide (the thickness is the average dimension measured in thedirection perpendicular to the propagating plane of the light within thecoupling lightguide) is greater than one selected from the group: 5:1,10:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, 60:1, 70:1, and 100:1. In oneembodiment, the thickness of the coupling lightguide is less than 600microns and the width is greater than 10 millimeters. In one embodiment,the thickness of the coupling lightguide is less than 400 microns andthe width is greater than 3 millimeters. In a further embodiment, thethickness of the coupling lightguide is less than 400 microns and thewidth is greater than 10 millimeters. In another embodiment, thethickness of the coupling lightguide is less than 300 microns and thewidth is less than 10 millimeters. In another embodiment, the thicknessof the coupling lightguide or light transmitting film is less than 200microns and the width is less than 20 millimeters. Imperfections at thelateral edges of the coupling lightguides (deviations from perfectplanar, flat surfaces due to the cutting of strips, for example) canincrease the loss of light through the edges or surfaces of the couplinglightguides. By increasing the width of the coupling lightguides, onecan reduce the effects of edge imperfections since the light within thecoupling lightguide bounces (reflects) less off of the lateral edgesurfaces (interacts less with the surface) in a wider couplinglightguide than a narrow coupling lightguide for a give range of anglesof light propagation. The width of the coupling lightguides is a factoraffecting the spatial color or luminance uniformity of the lightentering the lightguide region, light mixing region, or lightguide, andwhen the width of the coupling lightguide is large compared to the width(in that same direction) of the light emitting region, then spatiallynon-uniform regions can occur.

In another embodiment, the ratio of width of the light emitting surfacearea disposed to receive at least 10% of the light emitted from agrouping of coupling lightguides forming a light input coupler in adirection parallel to the width of the coupling lightguides to theaverage width of the coupling lightguides is greater than one selectedfrom the group: 5:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, 60:1, 70:1,100:1, 150:1, 200:1, 300:1, 500:1, and 1000:1. In another embodiment,the ratio of the total width of the total light emitting surfacedisposed to receive the light emitted from all of the couplinglightguides directing light toward the light emitting region or surfacealong the width to the average coupling lightguide width is greater thanone selected from the group: 5:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1,60:1, 70:1, 100:1, 150:1, 200:1, 300:1, 500:1, and 1000:1.

In one embodiment, the width of the coupling lightguide is greater thanone of the following: 1.1, 1.2, 1.3, 1.5, 1.8, 2, 3, 4, and 5 times thewidth of the light output surface of the light source disposed to couplelight into the coupling lightguide. In another embodiment, the largercoupling lightguide width relative to the width of the light outputsurface of the light source allows for a higher degree of collimation(lower angular full-width at half maximum intensity) by the lightcollimating edges of the coupling lightguides.

Light Turning Edges of the Coupling Lightguides

In one embodiment, one or more coupling lightguides have an edge shapethat optically turns by total internal reflection a portion of lightwithin the coupling lightguide such that the optical axis of the lightwithin the coupling lightguide is changed from a first optical axisangle to a second optical axis angle different than the first opticalaxis angle. More than one edge of one or more coupling lightguides mayhave a shape or profile to turn the light within the coupling lightguideand the edges may also provide collimation for portions of the lightpropagating within the coupling lightguides. For example, in oneembodiment, one edge of a stack of coupling lightguides is curved suchthat the optical axis of the light propagating within the lightguide isrotated by 90 degrees. In one embodiment, the angle of rotation of theoptical axis by one edge of a coupling lightguide is greater than one ofthe following: 10 degrees, 20 degrees, 40 degrees, 45 degrees, 60degrees, 80 degrees, 90 degrees, and 120 degrees. In another embodiment,the angle of rotation of the optical axis by more than one edge regionof a coupling lightguide is greater than one of the following: 10degrees, 20 degrees, 40 degrees, 45 degrees, 60 degrees, 80 degrees, 90degrees, 120 degrees, 135 degrees, and 160 degrees. By employing morethan one specifically curved edge, the light may be rotated to a widerange of angles. In one embodiment, the light within the couplinglightguide is redirected in a first direction (+theta direction) by afirst edge profile and rotated in a section direction (+theta 2) by asecond edge profile. In another embodiment, the light within thecoupling lightguide is redirected from a first direction to a seconddirection by a first edge profile and rotated back toward the firstdirection by a second edge profile region further along the couplinglightguide. In one embodiment, the light turning edges of the couplinglightguide are disposed in one or more regions including, withoutlimitation, near the light source, near the light input surface of thecoupling lightguides, near the light mixing region, near the lightguideregion, between the light input surface of the coupling lightguides,near the light mixing region, near the region between the couplinglightguides and the lightguide region, and near the lightguide region.

In one embodiment, one lateral edge near the light input surface of thecoupling lightguide has a light turning profile and the opposite lateraledge has a light collimating profile. In another embodiment, one lateraledge near the light input surface of the coupling lightguide has a lightcollimating profile followed by a light turning profile (in thedirection of light propagate away from the light input surface withinthe coupling lightguide).

In one embodiment, two arrays of stacked coupling lightguides aredisposed to receive light from a light source and rotate the opticalaxis of the light into two different directions. In another embodiment,a plurality of coupling lightguides with light turning edges may befolded and stacked along an edge of the lightguide region such thatlight from a light source oriented toward the lightguide region entersthe stack of folded coupling lightguides, the light turning edgesredirect the optical axis of the light to a first directionsubstantially parallel to the edge and the folds in the stacked couplinglightguides redirect the light to a direction substantially toward thelightguide region. In this embodiment, a second array of stacked, foldedcoupling lightguides can be stacked above or below (or interleaved with)the first array of stacked, folded coupling lightguides along the sameedge of the lightguide region such that light from the same light sourceoriented toward the lightguide region enters the second array ofstacked, folded coupling lightguides, the light turning edges of thesecond array of stack folded coupling lightguides redirect the opticalaxis of the light to a second direction substantially parallel to theedge (and opposite the first direction) and the folds in the stackedcoupling lightguides redirect the light to a direction substantiallytoward the lightguide region. In another embodiment, the couplinglightguides from two different arrays along an edge of a lightguideregion may be alternately stacked upon each other. The stackingarrangement may be predetermined, random, or a variation thereof. Inanother embodiment, a first stack of folded coupling lightguides fromone side of a non-folded coupling lightguide are disposed adjacent onesurface of the non-folded coupling lightguide and a second stack offolded coupling lightguides from the other side of the non-foldedcoupling lightguide are disposed adjacent the opposite surface of thenon-folded coupling lightguide. In this embodiment, the non-foldedcoupling lightguide may be aligned to receive the central (higher flux)region of the light from the light source when there are equal numbersof coupling lightguides on the top surface and the bottom surface of thenon-folded coupling lightguide. In this embodiment, the non-foldedcoupling lightguide may have a higher transmission (less light loss)since there are no folds or bends, thus more light reaches thelightguide region.

In another embodiment, the light turning edges of one or more couplinglightguides redirects light from two or more light sources with firstoptical axis angles to light having a second optical axis anglesdifferent than the first optical axis angles. In a further embodiment,the light turning edges of one or more coupling lightguides redirects afirst portion of light from a light source with a first optical axisangle to a portion of light having second optical axis angle differentthan the first optical axis angle. In another embodiment, the lightturning edges of one or more coupling lightguides redirects light from afirst light source with a first optical axis angle to light having asecond optical axis angle different from the first optical axis angleand light from a second light source with a third optical axis angle tolight having a fourth optical axis angle different from the thirdoptical axis angle.

In one embodiment, the light turning profile of one or more edges of acoupling lightguide has a curved shape when viewed substantiallyperpendicular to the film. In another embodiment, the curved shape hasone or more conic, circular arc, parabolic, hyperbolic, geometric,parametric, or other algebraic curve regions. In another embodiment, theshape of the curve is designed to provide improved transmission throughthe coupling lightguide by minimizing bend loss (increased reflection)for a particular light input profile to the coupling lightguide, lightinput surface, light profile modifications before the curve (such ascollimating edges for example), refractive indexes for the wavelengthsof interest for the coupling lightguide material, surface finish of theedge, and coating or cladding type at the curve edge (low refractiveindex material, air, or metallized for example). In one embodiment, thelight lost from the light turning profile of one or more edge regions ofthe coupling lightguide is less than one of the following: 50%, 40%,30%, 20%, 10%, and 5%.

Vertical Light Turning Edges

In one embodiment, the vertical edges of the coupling lightguides (theedges tangential to the larger film surface) or the core regions of thecoupling lightguides have a non-perpendicular cross-sectional profilethat rotates the optical axis of a portion of incident light. In oneembodiment, the vertical edges of one or more coupling lightguides orcore regions of the coupling lightguides comprise a curved edge. Inanother embodiment, the vertical edges of one or more couplinglightguides or core regions comprise an angled edge wherein the angle tothe surface normal of the coupling lightguide is greater than one of thefollowing: 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degreesand 60 degrees. In one embodiment, the use of vertical light turningedges of the core regions or coupling lightguides allows light to enterinto the coupling lightguides from the coupling lightguide film surfacewhere it is typically easier to obtain an optical finish as it can bethe optically smooth surface of a film. In another embodiment, thecoupling lightguides (or core regions of the coupling lightguides) arebrought in contact and the vertical edges are cut at an angle to thesurface normal. In one embodiment, the angled cut creates a smooth,continuous, angled vertical light turning edge on the edges of thecoupling lightguides. In another embodiment, the angled, curved, orcombination thereof vertical light turning edges are obtained by one ormore of the following: laser cutting, polishing, grinding, die cutting,blade cutting or slicing, and hot blade cutting or slicing. In oneembodiment, the vertical light turning edges are formed when thecoupling lightguides are cut into the lightguide film and the couplinglightguides are aligned to form a vertical light turning edge.

In another embodiment, the light input surface of the couplinglightguides is the surface of one or more coupling lightguides and thesurface comprises one or more surface relief profiles (such as anembossed Fresnel lens, microlens array, or prismatic structures) thatturns, collimates or redirects a portion of the light from the lightsource. In a further embodiment, a light collimating element, lightturning optical element, or light coupling optical element is disposedbetween the light source and the light input film surface of thecoupling lightguide (non-edge surface). In one embodiment, the lightinput film surface is the surface of the cladding region or the coreregion of the coupling lightguide. In a further embodiment, the lightcollimating optical element, light turning optical element, or lightcoupling optical element is optically coupled to the core region,cladding region, or intermediate light transmitting region between theoptical element and the coupling lightguide.

Vertical Light Collimating Edges

In one embodiment, the vertical edges of the coupling lightguide (theedges tangential to the larger film surface) or the core regions of thecoupling lightguides have a non-perpendicular cross-sectional profilethat collimate a portion of incident light. In one embodiment, thevertical edges of one or more coupling lightguides or core regions ofthe coupling lightguides comprise a curved edge that collimates aportion of incident light. In another embodiment, the vertical edges ofone or more coupling lightguides or core regions comprise an angled edgewherein the angle to the surface normal of the coupling lightguide isgreater than one of the following: 10 degrees, 20 degrees, 30 degrees,40 degrees, 50 degrees and 60 degrees.

Non-Folded Coupling Lightguide

In a further embodiment, the film-based lightguide comprises anon-folded coupling lightguide disposed to receive light from the lightinput surface and direct light toward the lightguide region withoutturning the light. In one embodiment, the non-folded lightguide is usedin conjunction with one or more light turning optical elements, lightcoupling optical elements, coupling lightguides with light turningedges, or coupling lightguides with collimating edges. For example, alight turning optical element may be disposed above or below anon-folded coupling lightguide such that a first portion of light from alight source substantially maintains the direction of its optical axiswhile passing through the non-folded coupling lightguide and the lightfrom the source received by the light turning optical element is turnedto enter into a stacked array of coupling lightguides. In anotherembodiment, the stacked array of coupling lightguides comprises foldedcoupling lightguides and a non-folded coupling lightguide.

In another embodiment, the non-folded coupling lightguide is disposednear an edge of the lightguide. In one embodiment, the non-foldedcoupling lightguide is disposed in the middle region of the edge of thelightguide region. In a further embodiment, the non-folded couplinglightguide is disposed along a side of the lightguide region at a regionbetween the lateral sides of the lightguide region. In one embodiment,the non-folded coupling lightguide is disposed at various regions alongone edge of a lightguide region wherein a plurality of light inputcouplers are used to direct light into the side of a lightguide region.

In another embodiment, the folded coupling lightguides have lightcollimating edges, substantially linear edges, or light turning edges.In one embodiment, at least one selected from the group: the array offolded coupling lightguides, light turning optical element, lightcollimating optical element, and light source are physically coupled tothe non-folded coupling lightguide. In another embodiment, foldedcoupling lightguides are physically coupled to each other and to thenon-folded coupling lightguide by a pressure sensitive adhesive claddinglayer and the thickness of the unconstrained lightguide film comprisingthe light emitting region and the array of coupling lightguides is lessthan one of the following: 1.2 times, 1.5 times, 2 times, and 3 timesthe thickness of the array of coupling lightguides. By bonding thefolded coupling lightguides only to themselves, the coupling lightguides(when un-constrained) typically bend upward and increase the thicknessof the array due to the folded coupling lightguides not being physicallycoupled to a fixed or relatively constrained region. By physicallycoupling the folded coupling lightguides to a non-folded couplinglightguide, the array of coupling lightguides is physically coupled to aseparate region of the film which increases the stability and thusreduces the ability of the elastic energy stored from the bend to bereleased.

In one embodiment, the non-folded coupling lightguide comprises one ormore of the following: light collimating edges, light turning edges,angled linear edges, and curved light redirecting edges. The non-foldedcoupling lightguide or the folded coupling lightguides may comprisecurved regions near bend regions, turning regions, or collimatingregions such that stress (such as resulting from torsional or lateralbending) does not focus at a sharp corner and increase the likelihood offracture. In another embodiment, curved regions are disposed where thecoupling lightguides join with the lightguide region or light mixingregion of the film-based lightguide.

In another embodiment, at least one selected from the group: non-foldedcoupling lightguide, folding coupling lightguide, light collimatingelement, light turning optical element, light redirecting opticalelement, light coupling optical element, light mixing region, lightguideregion, and cladding region of one or more elements is physicallycoupled to the relative position maintaining element. By physicallycoupling the coupling lightguides directly or indirectly to the relativeposition maintaining element, the elastic energy stored from the bend inthe coupling lightguides held within the coupling lightguides and thecombined thickness of the unconstrained coupling lightguides(unconstrained by an external housing for example) is reduced.

Interior Light Directing Edge

In one embodiment, the interior region of one or more couplinglightguides comprises an interior light directing edge. The interiorlight redirecting edge may be formed by cutting or otherwise removing aninterior region of the coupling lightguide. In one embodiment, theinterior light directed edge redirects a first portion of light withinthe coupling lightguide. In one embodiment, the interior lightredirecting edges provide an additional level of control for directingthe light within the coupling lightguides and can provide light fluxredistribution within the coupling lightguide and within the lightguideregion to achieve a predetermined light output pattern (such as higheruniformity or higher flux output in a specific region).

Cavity Region within the Coupling Lightguides

In one embodiment, one or more coupling lightguides or core regions ofcoupling lightguides comprises at least one cavity. In anotherembodiment, the cavity is disposed to receive the light source and thevertical edges of the core regions of the coupling lightguides arevertical light collimating optical edges. In one embodiment, a higherflux of light is coupled within the coupling lightguides with a cavityin at least one coupling lightguide than is coupled into the couplinglightguides without the cavity. This may be evaluated, for example, bymeasuring the light flux out of the coupling lightguides (when cut) orout of the light emitting device with an integrating sphere before andafter filling the cavity with a high transmittance (>90% transmittance)light transmitting material (with the light source disposed adjacent thecorresponding surface of the material) that is index-matched with thecore region. In another embodiment, the cavity region providesregistration or alignment of the coupling lightguides with the lightsource and increased light flux coupling into the coupling lightguides.In one embodiment, an array of coupling lightguides with vertical lightcollimating edges and a cavity alleviates the need for a lightcollimating optical element.

Coupling Lightguides Comprising Coupling Lightguides

In one embodiment, at least one coupling lightguide comprises aplurality of coupling lightguides. For example, a coupling lightguidemay be further cut to comprise a plurality of coupling lightguides thatconnect to the edge of the coupling lightguide. In one embodiment, afilm of thickness T comprises a first array of N number of couplinglightguides, each comprising a sub-array of M number of couplinglightguides. In this embodiment, the first array of coupling lightguidesis folded in a first direction such that the coupling lightguides arealigned and stacked, and the sub-array of coupling lightguides is foldedin a second direction such that the coupling lightguides are aligned andstacked. In this embodiment, the light input edge surface comprising thesub-array of coupling lightguides has a width the same as each of thenarrower coupling lightguides and the light input surface has a height,H, defined by H=T×N×M. This can, for example, allow for the use of athinner lightguide film to be used with a light source with a muchlarger dimension of the light output surface. In one embodiment, thinfilm-based lightguides are utilized, for example, when the film-basedlightguide is the illuminating element of a frontlight disposed above atouchscreen in a reflective display. A thin lightguide in thisembodiment provides a more accurate, and responsive touchscreen (such aswith capacitive touchscreens for example) when the user touches thelightguide film. Alternatively, a light source with a larger dimensionof the light output surface may be used for a specific lightguide filmthickness.

Another advantage of using coupling lightguides comprising a pluralityof coupling lightguides is that the light source can be disposed withinthe region between the side edges of the lightguide region and thus notextend beyond an edge of the display or light emitting region when thelight source and light input coupler are folded behind the lightemitting surface, for example.

Number of Coupling Lightguides in a Light Input Coupler

In one embodiment, the total number of coupling lightguides, NC, in adirection parallel to the light entrance edge of the lightguide regionor lightguide receiving light from the coupling lightguide isNC=MF*WLES/w, where WLES is the total width of the light emittingsurface in the direction parallel to the light entrance edge of thelightguide region or lightguide receiving light from the couplinglightguide, w is the average width of the coupling lightguides, and MFis the magnification factor. In one embodiment, the magnification factoris one selected from the group: 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4,0.7-1.3, 0.8-1.2, and 0.9-1.1. In another embodiment, the number ofcoupling lightguides in a light input coupler or the total number ofcoupling lightguides in the light emitting device is selected from thegroup: 2, 3, 4, 5, 6, 8, 10, 11, 20, 30, 50, 70, 80, 90, 100, 2-50,3-50, 4-50, 2-500, 4-500, greater than 10, greater than 20, greater than30, greater than 40, greater than 50, greater than 60, greater than 70,greater than 80, greater than 90, greater than 100, greater than 120,greater than 140, greater than 200, greater than 300, greater than 400,greater than 500.

Coupling Lightguides Directed into More than One Light Input Surface

In a further embodiment, the coupling lightguides collectively do notcouple light into the light mixing region, lightguide, or light mixingregion in a contiguous manner. For example, every other couplinglightguide may be cut out from the film-based lightguide while stillproviding strips or coupling lightguides along one or more edges, butnot continuously coupling light into the lightguide regions. By usingfewer lightguides, the collection of light input edges may be reduced insize. This reduction in size, for example, can be used to combinemultiple sets of coupling lightguides optically coupled to differentregions of the same lightguide or a different lightguide, better matchthe light input surface size to the light source size, use a smallerlight source, or use a thicker lightguide film with a particular lightsource where the dimension of the set of contiguous coupling lightguidesin the thickness direction would be one selected from the group: 10%,20%, 40%, 50%, and 100% greater than light emitting surface of the lightsource in the thickness direction when disposed to couple light into thelight input surface.

In a further embodiment, coupling lightguides from a first region of alightguide have light input edges collected into two or more light inputsurfaces. For example, the odd number coupling lightguides may bedirected to a first white light source and the even number couplinglightguides may be coupled to a red, green, and blue light source. Inanother embodiment, the coupling lightguides from a first region of alightguide are coupled to a plurality of white light sources to reducevisibility of color variations from the light source. For example, theeven number coupling lightguides may couple light from a white lightsource with a first color temperature and the odd number couplinglightguides may couple light from a white light source with a secondcolor temperature higher than the first such that the colornon-uniformity, Δu′v′, along a direction parallel to an edge of thelightguide region along the light emitting surface is less than oneselected from the group: 0.2, 0.1, 0.05, 0.01, and 0.004.

Similarly, three or more light input surfaces may also be used to couplelight from 1, 2, 3 or more light sources. For example, every alternatingfirst, second, and third coupling lightguide from a first region of alightguide are directed to a first, second, and third light source ofthe same or different colors.

In a further embodiment, coupling lightguides from a first region of alightguide have light input edges collected into two or more light inputsurfaces disposed to couple light into the lightguide for differentmodes of operation. For example, the first light input surface may becoupled to at least one light source suitable for daylight compatibleoutput and the second light input surface may be coupled to at least onelight source for NVIS compatible light output.

The order of the coupling lightguides directed to more than one lightinput surface does not need to be alternating and may be of anypredetermined or random configuration. For example, the couplinglightguides from the top and bottom region of the lightguide may bedirected to a different light input surface than the middle region. In afurther embodiment, the coupling lightguides from a region of thelightguide are disposed together into a plurality of light inputsurfaces, each comprising more than one light input edge, arranged in anarray, disposed to couple light from a collection of light sources,disposed within the same housing, disposed such that the light inputsurfaces are disposed adjacent each other, disposed in an ordertransposed to receive light from a collection of light sources, disposedin a non-contiguous arrangement wherein neighboring light input surfacesdo not couple light into neighboring regions of the lightguide,lightguide region, or light mixing region.

In a further embodiment, a plurality of sets of coupling lightguides arearranged to provide a plurality of sets of light input surface along thesame side, edge, the back, the front or within the same housing regionof the light emitting device wherein the plurality of light inputsurfaces are disposed to receive light from one or a plurality of LEDs.

Order of Coupling Lightguides

In one embodiment, the coupling lightguides are disposed together at alight input edge forming a light input surface such that the order ofthe strips in a first direction is the order of the coupling lightguidesas they direct light into the lightguide or lightguide region. Inanother embodiment, the coupling lightguides are interleaved such thatthe order of the strips in a first direction is not the same as theorder of the coupling lightguides as they direct light into thelightguide or lightguide region. In one embodiment, the couplinglightguides are interleaved such that at least one coupling lightguidereceiving light from a first light source of a first color is disposedbetween two coupling lightguides at a region near the lightguide regionor light mixing region that receive light from a second light sourcewith a second color different from the color of the first light source.In one embodiment, the color non-uniformity, Δu′v′, along a directionparallel to the edge of the lightguide region along the light emittingsurface is less than one selected from the group: 0.2, 0.1, 0.05, 0.01,and 0.004. In another embodiment, the coupling lightguides areinterleaved such that at least one pair of coupling lightguides adjacentto each other at the output region of the light input coupler near thelight mixing region, lightguide, or lightguide region, are not adjacentto each other near the input surface of the light input coupler. In oneembodiment, the interleaved coupling lightguides are arranged such thatthe non-uniform angular output profile is made more uniform at theoutput of the light input coupler by distributing the couplinglightguides such that output from the light input coupler does notspatially replicate the angular non-uniformity of the light source. Forexample, the strips of a light input coupler could alternate among fourdifferent regions of the lightguide region as they are combined at thelight input surface so that the middle region would not have very highluminance light emitting surface region that corresponds to thetypically high intensity from a light source at 0 degrees or along itsoptical axis.

In another embodiment, the coupling lightguides are interleaved suchthat at least one pair of coupling lightguides adjacent to each othernear the light mixing region, lightguide, or lightguide region, do notreceive light from at least one of the same light source, the same lightinput coupler, and the same mixing region. In another embodiment, thecoupling lightguides are interleaved such that at least one pair ofcoupling lightguides adjacent to each other near a light input surfacedo not couple light to at least one of the same light input coupler, thesame light mixing region, the same lightguide, the same lightguideregion, the same film, the same light output surface. In anotherembodiment, the coupling lightguides are interleaved at the light inputsurface in a two-dimensional arrangement such that at least twoneighboring coupling lightguides in a vertical, horizontal or otherdirection at the input surface do not couple light to a neighboringregion of at least one selected from the group: the same light inputcoupler, the same light mixing region, the same lightguide, the samelightguide region, the same film, and the same light output surface.

In a further embodiment, coupling lightguides optically coupled to thelightguide region, light mixing region, or light emitting region near afirst input region are arranged together in a holder disposedsubstantially along or near a second edge region which is disposed alongan edge direction greater than one selected from the group: 30 degrees,40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees and 85degrees to first edge region. For example, light input couplers maycouple light from a first light source and coupling lightguide holderdisposed along the bottom edge of a liquid crystal display and directthe light into the region of the lightguide disposed along a side of thedisplay oriented about 90 degrees to the bottom edge of the display. Thecoupling lightguides may direct light from a light source disposed alongthe top, bottom, or both into one or more sides of a display such thatthe light is substantially propagating parallel to the bottom and topedges within the lightguide region.

Coupling Lightguides Bonded to the Surface of a Lightguide Region

In one embodiment, the coupling lightguides are not segmented (or cut)regions of the same film which comprises the lightguide or lightguideregion. In one embodiment, the coupling lightguides are formed andphysically or optically attached to the lightguide, light mixing region,or lightguide region using at least one selected from the group: opticaladhesive, bonding method (solvent welding, thermally bonding, ultrasonicwelding, laser welding, hot gas welding, freehand welding, speed tipwelding, extrusion welding, contact welding, hot plate welding, highfrequency welding, injection welding, friction welding, spin welding,welding rod), and adhesive or joining techniques suitable for polymers.In one embodiment, the coupling lightguides are formed and opticallycoupled to the lightguide, mixing region, or lightguide region such thata significant portion of the light from the coupling lightguides istransferred into a waveguide condition within the mixing region,lightguide region, or lightguide. The coupling lightguide may beattached to the edge or a surface of the light mixing region, lightguideregion, or lightguide. In one embodiment, the coupling lightguides aredisposed within a first film wherein a second film comprising alightguide region is extruded onto a region of the first film such thatthe coupling lightguides are optically coupled to the lightguide region.In another embodiment, the coupling lightguides are tapered in a regionoptically coupled to the lightguide. By separating out the production ofthe coupling lightguides with the production of the lightguide region,materials with different properties may be used for each region such asmaterials with different optical transmission properties, flexuralmodulus of elasticity, impact strength (Notched Izod), flexuralrigidity, impact resistance, mechanical properties, physical properties,and other optical properties. In one embodiment, the couplinglightguides comprise a material with a flexural modulus less than 2gigapascals and the lightguide or lightguide region comprises a materialwith a flexural modulus greater than 2 gigapascals measured according toASTM D790. In one embodiment, the lightguide is a relatively stiffpolycarbonate material and the coupling lightguides comprise a flexibleelastomer or polyethylene. In another embodiment, the lightguide is anacrylic material and the coupling lightguides comprise a flexiblefluoropolymer, elastomer or polyethylene. In one embodiment, the averagethickness of the lightguide region or lightguide is more than 0.1 mmthicker than the average thickness of at least one coupling lightguide.

In one embodiment, at least one coupling lightguide is optically coupledto at least one selected from the group: surface, edge, or interiorregion, of an input light coupler, light mixing region, lightguideregion, and lightguide. In another embodiment, a film comprisingparallel linear cuts along a direction of a film is bonded to a surfaceof a film in the extrusion process such that the strips are opticallycoupled to the lightguide film and the cut regions can be cut in thetransverse direction to “free” the strips so that they can be broughttogether to form a light input surface of a light input coupler.

Coupling Lightguides Ending within the Lightguide Region

In one embodiment, a film comprising parallel linear cuts along themachine direction of a film is guided between two extrusion layers orcoatings such that the ends of the strips are effectively inside theother two layers or regions. In another embodiment, one or more edges ofthe coupling lightguide are optically couple to a layer or coating (suchas an adhesive) within a lightguide to reduce scattering and increaselight coupling into the lightguide. This could be done in a single stepor in sequential steps. By having strips or coupling lightguidesterminate within a lightguide, lightguide region, or light mixingregion, there are fewer back reflections from the air-end edge interfaceas there would be on a simple surface bonding because the edge wouldeffectively be optically coupled into the volume of the lighttransmitting material forming the light mixing region, lightguide regionor lightguide (assuming the material near the edge could flow or deformaround the edge or another material is used (such as an adhesive) topromote the optical coupling of the edge and potentially surfaces.

Strip or Coupling Lightguide Registration or Securing Feature

In one embodiment, at least one strip near the central region of a lightinput coupler is used to align or guide the coupling strips or toconnect the coupling lightguides to a lightguide or housing. In afold-design wherein the coupling lightguides are folded toward thecenter of the light input coupler, a central strip or lightguide may notbe folded to receive light from the light source due to geometricallimitations on the inability to fold the central strip or couplinglightguide. This central strip or coupling lightguide may be used forone selected from the group: aligning the light input coupler or housingto the strips (or lightguide), tightening the fold of the strips orcoupling lightguide stack to reduce the volume, registering, securing orlocking down the position of the light input coupler housing, provide alever or arm to pull together components of a folding mechanism whichbend or fold the coupling lightguides, coupling lightguides, lightguideor other element relative to one of the aforementioned elements.

Tab Region

In one embodiment, one or more of the strips or coupling lightguidescomprises a tab or tab region that is used to register, align, or securethe location of the strip or coupling lightguide relative to thehousing, folder, holder, lightguide, light source, light input coupler,or other element of the light emitting device. In another embodiment, atleast one strip or coupling lightguide comprises a pin, hole, cut-out,tab, or other feature useful for registering, aligning, or securing thelocation of the strip or coupling lightguide. In one embodiment, the tabregion is disposed at a side of one or more light sources when the lightsource is disposed to couple light into a coupling lightguide. In afurther embodiment, the tab region may be removed, by tearing forexample, after the stacking of the coupling lightguides. For example,the coupling lightguides may have an opening or aperture cut within thecoupling lightguides that align to form a cavity within which the lightemitting region of the light source may be disposed such that the lightfrom the light source is directed into the light input surfaces of thecoupling lightguides. After physically constraining the couplinglightguides (by adhering them to each other or to another element or bymechanical clamping, alignment guide or other means for example), all ora portion of the tab region may be removed by tearing without reducingthe optical quality of the light input surface disposed to receive lightfrom the light source. In another embodiment, the tab region comprisesone or more perforations or cut regions that promote the tearing orremoval of the tab region along a predetermined path.

In another embodiment, the tab region or region of the couplinglightguides comprising registration or alignment openings or aperturesare stacked such that the openings or apertures align onto aregistration pin or post disposed on or physically coupled to the lightturning optical element, light collimating optical element, lightcoupling element, light source, light source circuit board, relativeposition maintaining element, light input coupler housing, or otherelement of the light input coupler such that the light input surfaces ofthe coupling lightguides are aligned and disposed to receive light fromthe element or light source.

The tab region may comprise registration openings or apertures on eitherside of the openings or apertures forming the cavity in couplinglightguide such that registration pins assist in the aligning andrelative positioning of the coupling lightguides. In another embodiment,one or more coupling lightguides (folded non-folded) comprise low lightloss registration openings or apertures in a low light flux region. Lowlight loss registration openings or apertures in low light flux regionsof the coupling lightguides are those wherein less than one of thefollowing: 2%, 5%, 10% and 20% of the light flux from a light sourcereaches the opening or aperture directly or indirectly within a couplinglightguide. This can be measured by filling the openings or apertureswith a black light absorbing material such as a black latex paint andmeasuring the loss in light output from the light emitting region usingan integrating sphere.

In another embodiment, the tab regions of the coupling lightguides allowfor the light input surface of the stacked array of coupling lightguidesto be formed after stacking the coupling lightguides such that animproved optical finish of the light input surface can be obtained. Forexample, in one embodiment, the array of coupling lightguides is stackedwith a tab region extended from the input region of the couplinglightguides. The stacked array is then cut in the tab region (andoptionally mechanically, thermally, chemically or otherwise polished) toprovide a continuous smooth input surface.

Holding the Coupling Lightguide Position Relative to the Light Source orOptical Element

In another embodiment, the tab region may be cut to provide a physicallyconstraining mechanism for an optical element or the light source. Forexample, in one embodiment, the tab region of the coupling lightguidescomprises one or more arms or ridges such that when the couplinglightguides are stacked in an array, the arms or ridges form aconstraining groove or cavity to substantially maintain the opticalelement or light source in at least one direction. In anotherembodiment, the stacked array of coupling lightguides form a cavity thatallows an extended ridge of a light collimating optic to be positionedwithin the cavity such that the light collimating optic substantiallymaintains its position relative to the coupling lightguides. Variousforms of grooves, ridges, interlocking shapes, pins, openings, aperturesand other constraining shapes may be used with the optical element (suchas the light turning optical element or light collimating opticalelement) or the light source (or housing of the light source) and theshape cut into the coupling lightguides to constrain the element orlight source when placed into the interlocking shape.

Extended Coupling Lightguides

In one embodiment, the coupling lightguides are extended such that thecoupling lightguides may be folded in an organized fashion by using arelative position maintaining element. By extending the couplinglightguides, the relative position and order of the coupling lightguidesmay be maintained during the aligning and stacking process such that thecoupling lightguides may be stacked and aligned in an organized fashion.For example, in one embodiment, the coupling lightguides are extendedwith an inverted shape such that they are mirrored along a firstdirection. In one embodiment, the folding operation creates two stackedarrays of coupling lightguides which may be used to form two differentlight emitting devices or two illuminated regions illuminated by thesame light source. In another embodiment, a first relative positionmaintaining element substantially maintains the relative position of thecoupling lightguides near a first lightguide region and a secondrelative position maintaining element substantially maintains therelative position of the extended regions of the coupling lightguides(which may form the coupling lightguides of a second light emittingdevice or region).

Varying Coupling Lightguide Thickness

In one embodiment, at least one coupling lightguide or strip varies inthe thickness direction along the path of the light propagating throughthe lightguide. In one embodiment, at least one coupling lightguide orstrip varies in the thickness direction substantially perpendicular tothe path of the light propagating through the lightguide. In anotherembodiment, the dimension of at least one coupling lightguide or stripvaries in a direction parallel to the optical axis of the light emittingdevice along the path of the light propagating through the lightguide.In one embodiment, the thickness of the coupling lightguide increases asthe light propagates from a light source to the light mixing region,lightguide, or lightguide region. In one embodiment, the thickness ofthe coupling lightguide decreases as the light propagates from a lightsource to the light mixing region, lightguide, or lightguide region. Inone embodiment, the thickness of a coupling lightguide in a first regiondivided by the thickness of the coupling lightguide in a second regionis greater than one selected from the group: 1, 2, 4, 6, 10, 20, 40, 60and 100.

Light Turning Optical Elements or Edges for Light Source Placement

In one embodiment, the light turning optical elements or light turningcoupling lightguide edges may be used to position the light source onthe same side of the lightguide region as the coupling lightguides. Inanother embodiment, the light turning optical elements or light turningcoupling lightguide edges may be used to position the light sourcewithin the extended boundaries of the coupling lightguides such that thelight source does not extend past an edge of the lightguide, lightemitting region, edges of the display area, lightguide region or bevel.For example, a film-based lightguide with coupling lightguides foldedalong one edge may have angled edges or a region of the lightguideregion not to be directly illuminated from a coupling lightguide inorder to position the light source within the region bounded by theedges of the lightguide region. Alternatively, the stack of couplinglightguides along one edge may have light turning edges near the lightsource ends such that the light source can be disposed with lightdirected toward the lightguide region. This can allow the light to beturned and directed into the coupling lightguides and when the lightsource is folded behind the display, the light source does not extendpast the outer display edges.

Light Mixing Region

In one embodiment, a light emitting device comprises a light mixingregion disposed in an optical path between the light input coupler andthe lightguide region. The light mixing region can provide a region forthe light output from individual coupling lightguides to mix togetherand improve at least one of the spatial luminance uniformity, spatialcolor uniformity, angular color uniformity, angular luminanceuniformity, angular luminous intensity uniformity or any combinationthereof within a region of the lightguide or of the surface or output ofthe light emitting region or light emitting device. In one embodiment,the width of the light mixing region is selected from a range from 0.1mm (for small displays) to more than 3.048 meters (for largebillboards). In one embodiment, the light mixing region is the regiondisposed along an optical path near the end region of the couplinglightguides whereupon light from two or more coupling lightguides mayinter-mix and subsequently propagate to a light emitting region of thelightguide. In one embodiment, the light mixing region is formed fromthe same component or material as at least one of the lightguide,lightguide region, light input coupler, and coupling lightguides. Inanother embodiment, the light mixing region comprises a material that isdifferent than at least one selected from the group: the lightguide,lightguide region, light input coupler, and coupling lightguides. Thelight mixing region may be a rectangular, square or other shaped regionor it may be a peripheral region surrounding all or a portion of thelight emitting region or lightguide region. In one embodiment, thesurface area of the light mixing region of a light emitting device isone selected from the group: less than 1%, less than 5%, less than 10%,less than 20%, less than 30%, less than 40%, less than 50%, less than60%, less than 70%, greater than 20%, greater than 30%, greater than 40%greater than 50%, greater than 60%, greater than 70%, greater than 80%,greater than 90%, 1-10%, 10-20%, 20-50%, 50-70%, 70-90%, 80-95% of thetotal outer surface area of the light emitting surface or the area ofthe light emitting surface from which light is emitted.

In one embodiment, a film-based lightguide comprises a light mixingregion with a lateral dimension longer than a coupling lightguide widthand the coupling lightguides do not extend from the entire edge regioncorresponding to the light emitting region of the lightguide. In oneembodiment, the width of the gap along the edge without a couplinglightguide is greater than one of the following: 1 times, 2 times, 3times, or 4 times the average width of the neighboring couplinglightguides. In a further embodiment, the width of the gap along theedge without a coupling lightguide is greater than one of the following:1 times, 2 times, 3 times, or 4 times the lateral width of the lightmixing region. For example, in one embodiment, a film-based lightguidecomprises coupling lightguides with a width of 2 centimeters disposedalong a light mixing region that is 4 centimeters long in the lateraldirection (such as can readily be the case if the light mixing regionfolds behind a reflective display for a film-based frontlight), exceptin a central region where there is a 2-centimeter gap without a couplinglightguide extension. In this embodiment, the light within theneighboring coupling lightguides may spread into the gap region of thelight mixing region not illuminated by a coupling lightguide directlyand mix together such that the light in the light emitting area issufficiently uniform. In a further embodiment, a light mixing regioncomprises two or more gaps without coupling lightguides extendingtherefrom. In a further embodiment, a light mixing region comprisesalternating gaps between the coupling lightguide extensions along anedge of a film-based lightguide.

Cladding Layer

In one embodiment, at least one of the light input coupler, couplinglightguide, light mixing region, lightguide region, and lightguidecomprises a cladding layer optically coupled to at least one surface. Acladding region, as used herein, is a layer optically coupled to asurface wherein the cladding layer comprises a material with arefractive index, n_(clad), less than the refractive index of thematerial, nm, of the surface to which it is optically coupled. In oneembodiment, n_(m)-n_(clad) is one selected from the group: 0.001-0.005,0.001-0.01, 0.001-0.1, 0.001-0.2, 0.001-0.3, 0.001-0.4, 0.01-0.1,0.1-0.5, 0.1-0.3, 0.2-0.5, greater than 0.01, greater than 0.1, greaterthan 0.2, and greater than 0.3. In one embodiment, the cladding is oneselected from the group: methyl based silicone pressure sensitiveadhesive, fluoropolymer material (applied with using coating comprisinga fluoropolymer substantially dissolved in a solvent), and afluoropolymer film. The cladding layer may be incorporated to provide aseparation layer between the core or core part of a lightguide regionand the outer surface to reduce undesirable out-coupling (for example,frustrated totally internally reflected light by touching the film withan oily finger) from the core or core region of a lightguide. Componentsor objects such as additional films, layers, objects, fingers, dust etc.that come in contact or optical contact directly with a core or coreregion of a lightguide may couple light out of the lightguide, absorblight or transfer the totally internally reflected light into a newlayer. By adding a cladding layer with a lower refractive index than thecore, a portion of the light will totally internally reflect at thecore-cladding layer interface. Cladding layers may also be used toprovide the benefit of at least one of increased rigidity, increasedflexural modulus, increased impact resistance, anti-glare properties,provide an intermediate layer for combining with other layers such as inthe case of a cladding functioning as a tie layer or a base or substratefor an anti-reflection coating, a substrate for an optical componentsuch as a polarizer, liquid crystal material, increased scratchresistance, provide additional functionality (such as a low-tackadhesive to bond the lightguide region to another element, a window“cling type” film such as a highly plasticized PVC). The cladding layermay be an adhesive, such as a low refractive index silicone adhesivewhich is optically coupled to another element of the device, thelightguide, the lightguide region, the light mixing region, the lightinput coupler, or a combination of one or more of the aforementionedelements or regions. In one embodiment, a cladding layer is opticallycoupled to a rear polarizer in a backlit liquid crystal display. Inanother embodiment, the cladding layer is optically coupled to apolarizer or outer surface of a front-lit display such as anelectrophoretic display, e-book display, e-reader display, MEMs typedisplay, electronic paper displays such as E-ink® display by E InkCorporation, reflective or partially reflective LCD display, cholestericdisplay, or other display capable of being illuminated from the front.In another embodiment, the cladding layer is an adhesive that bonds thelightguide or lightguide region to a component such as a substrate(glass or polymer), optical element (such as a polarizer, retarder film,diffuser film, brightness enhancement film, protective film (such as aprotective polycarbonate film), the light input coupler, couplinglightguides, or other element of the light emitting device. In oneembodiment, the cladding layer is separated from the lightguide orlightguide region core layer by at least one additional layer oradhesive.

In one embodiment, a region of cladding material is removed or is absentin the region wherein the lightguide layer or lightguide is opticallycoupled to another region of the lightguide wherein the cladding isremoved or absent such that light can couple between the two regions. Inone embodiment, the cladding is removed or absent in a region near anedge of a lightguide, lightguide region, strip or region cut from alightguide region, or coupling lightguide such that light nearing theedge of the lightguide can be redirected by folding or bending theregion back onto a region of the lightguide wherein the cladding hasbeen removed where the regions are optically coupled together. Inanother embodiment, the cladding is removed or absent in the regiondisposed between the lightguide regions of two coupling lightguidesdisposed to receive light from a light source or near a light inputsurface. By removing or not applying or disposing a cladding in theregion between the input ends of two or more coupling lightguidesdisposed to receive light from a light source, light is not directlycoupled into the cladding region edge.

Cladding Location

In one embodiment, the cladding region is optically coupled to at leastone selected from the group: lightguide, lightguide region, light mixingregion, one surface of the lightguide, two surfaces of the lightguide,light input coupler, coupling lightguides, and outer surface of thefilm. In another embodiment, the cladding is disposed in optical contactwith the lightguide, lightguide region, or layer or layers opticallycoupled to the lightguide and the cladding material is not disposed onone or more coupling lightguides. In one embodiment, the couplinglightguides do not comprise a cladding layer between the core regions inthe region near the light input surface or light source. In anotherembodiment, the core regions may be pressed or held together and theedges may be cut and/or polished after stacking or assembly to form alight input surface or a light turning edge that is flat, curved, or acombination thereof. In another embodiment, the cladding layer is apressure sensitive adhesive and the release liner for the pressuresensitive adhesive is selectively removed in the region of one or morecoupling lightguides that are stacked or aligned together into an arraysuch that the cladding helps maintain the relative position of thecoupling lightguides relative to each other. In another embodiment, theprotective liner is removed from the inner cladding regions of thecoupling lightguides and is left on one or both outer surfaces of theouter coupling lightguides. In another embodiment, the protective linerof at least one outer surface of the outer coupling lightguides isremoved such that the stack of coupling lightguides may be bonded to oneof the following: a circuit board, a non-folded coupling lightguide, alight collimating optical element, a light turning optical element, alight coupling optical element, a flexible connector or substrate for adisplay or touchscreen, a second array of stacked coupling lightguides,a light input coupler housing, a light emitting device housing, athermal transfer element, a heat sink, a light source, an alignmentguide, a registration guide or component comprising a window for thelight input surface, and any suitable element disposed on and/orphysically coupled to an element of the light input surface or lightemitting device. In one embodiment, the coupling lightguides do notcomprise a cladding region on either planar side and optical loss at thebends or folds in the coupling lightguides is reduced. In anotherembodiment, the coupling lightguides do not comprise a cladding regionon either planar side and the light input surface input couplingefficiency is increased due to the light input surface area having ahigher concentration of lightguide received surface relative to alightguide with at least one cladding. In a further embodiment, thelight emitting region has at least one cladding region or layer and thepercentage of the area of the light input surface of the couplinglightguides disposed to transmit light into the lightguide portion ofthe coupling lightguides is greater than one of the following: 70%, 80%,85%, 90%, 95%, 98% and 99%. The cladding may be on one side only of thelightguide or the light emitting device could be designed to beoptically coupled to a material with a refractive index lower than thelightguide, such as in the case with a plasticized PVC film (n=1.53) (orother low-tack material) temporarily adhered to a glass window (n=1.51).

In one embodiment, the cladding on at least one surface of thelightguide is applied (such as coated or co-extruded) and the claddingon the coupling lightguides is subsequently removed. In a furtherembodiment, the cladding applied on the surface of the lightguide (orthe lightguide is applied onto the surface of the cladding) such thatthe regions corresponding to the coupling lightguides do not have acladding. For example, the cladding material could be extruded or coatedonto a lightguide film in a central region wherein the outer sides ofthe film will comprise coupling lightguides. Similarly, the cladding maybe absent on the coupling lightguides in the region disposed in closeproximity to one or more light sources or the light input surface.

In one embodiment, two or more core regions of the coupling lightguidesdo not comprise a cladding region between the core regions in a regionof the coupling lightguide disposed within a distance selected from thegroup: 1 millimeter, 2 millimeters, 4 millimeters, and 8 millimetersfrom the light input surface edge of the coupling lightguides. In afurther embodiment, two or more core regions of the coupling lightguidesdo not comprise a cladding region between the core regions in a regionof the coupling lightguide disposed within a distance selected from thegroup: 10%, 20%, 50%, 100%, 200%, and 300% of the combined thicknessesof the cores of the coupling lightguides disposed to receive light fromthe light source from the light input surface edge of the couplinglightguides. In one embodiment, the coupling lightguides in the regionproximate the light input surface do not comprise cladding between thecore regions (but may contain cladding on the outer surfaces of thecollection of coupling lightguides) and the coupling lightguides areoptically coupled together with an index-matching adhesive or materialor the coupling lightguides are optically bonded, fused, orthermo-mechanically welded together by applying heat and pressure. In afurther embodiment, a light source is disposed at a distance to thelight input surface of the coupling lightguides less than one selectedfrom the group: 0.5 millimeter, 1 millimeter, 2 millimeters, 4millimeters, and 6 millimeters and the dimension of the light inputsurface in the first direction parallel to the thickness direction ofthe coupling lightguides is greater than one selected from the group:100%, 110%, 120%, 130%, 150%, 180%, and 200% the dimension of the lightemitting surface of the light source in the first direction. In anotherembodiment, disposing an index-matching material between the coreregions of the coupling lightguides or optically coupling or boding thecoupling lightguides together in the region proximate the light sourceoptically couples at least one selected from the group: 10%, 20%, 30%,40%, and 50% more light into the coupling lightguides than would becoupled into the coupling lightguides with the cladding regionsextending substantially to the light input edge of the couplinglightguide. In one embodiment, the index-matching adhesive or materialhas a refractive index difference from the core region less than oneselected from the group: 0.1, 0.08, 0.05, and 0.02. In anotherembodiment, the index-matching adhesive or material has a refractiveindex greater by less than one selected from the group: 0.1, 0.08, 0.05,and 0.02 the refractive index of the core region. In a furtherembodiment, a cladding region is disposed between a first set of coreregions of coupling lightguides for a second set of coupling lightguidesan index-matching region is disposed between the core regions of thecoupling lightguides or they are fused together. In a furtherembodiment, the coupling lightguides disposed to receive light from thegeometric center of the light emitting area of the light source within afirst angle of the optical axis of the light source have claddingregions disposed between the core regions, and the core regions atangles larger than the first angle have index-matching regions disposedbetween the core regions of the coupling lightguides or they are fusedtogether. In one embodiment, the first angle is selected from the group:10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, and 60degrees. In the aforementioned embodiments, the cladding region may be alow refractive index material or air. In a further embodiment, the totalthickness of the coupling lightguides in the region disposed to receivelight from a light source to be coupled into the coupling lightguides isless than n times the thickness of the lightguide region where n is thenumber of coupling lightguides. In a further embodiment, the totalthickness of the coupling lightguides in the region disposed to receivelight from a light source to be coupled into the coupling lightguides issubstantially equal to n times the thickness of the lightguide layerwithin the lightguide region.

Cladding Layer Materials

In one embodiment, the cladding layer comprises an adhesive such as asilicone-based adhesive, acrylate-based adhesive, epoxy, radiationcurable adhesive, UV curable adhesive, or other light transmittingadhesive. The cladding layer material may comprise light scatteringdomains and may scatter light anisotropically or isotropically. In oneembodiment, the cladding layer is an adhesive such as those described inU.S. Pat. No. 6,727,313. In another embodiment, the cladding materialcomprises domains less than 200 nm in size with a low refractive indexsuch as those described in U.S. Pat. No. 6,773,801. Other low refractiveindex materials, fluoropolymer materials, polymers and adhesives may beused such as those disclosed U.S. Pat. Nos. 6,887,334 and 6,827,886 andU.S. patent application Ser. No. 11/795,534.

Fluoropolymer materials may be used as a low refractive index claddingmaterial and may be broadly categorized into one of two basic classes. Afirst class includes those amorphous fluoropolymers comprisinginterpolymerized units derived from vinylidene fluoride (VDF) andhexafluoropropylene (HFP) and optionally tetrafluoroethylene (TFE)monomers. Examples of such are commercially available from 3M Company asDyneon™ Fluoroelastomer FC 2145 and FT 2430. Additional amorphousfluoropolymers that can be used in embodiments are, for example,VDF-chlorotrifluoroethylene copolymers. One suchVDF-chlorotrifluoroethylene copolymer is commercially known as Kel-F™3700, available from 3M Company. As used herein, amorphousfluoropolymers are materials that contain essentially no crystallinityor possess no significant melting point as determined for example bydifferential scanning caloriometry (DSC). For the purpose of thisdiscussion, a copolymer is defined as a polymeric material resultingfrom the simultaneous polymerization of two or more dissimilar monomersand a homopolymer is a polymeric material resulting from thepolymerization of a single monomer.

The second significant class of fluoropolymers useful in an embodimentare those homo and copolymers based on fluorinated monomers such as TFEor VDF which do contain a crystalline melting point such aspolyvinylidene fluoride (PVDF, available commercially from 3M company asDyneon™ PVDF, or more preferable thermoplastic copolymers of TFE such asthose based on the crystalline microstructure of TFE-HFP-VDF. Examplesof such polymers are those available from 3M under the trade nameDyneon™ Fluoroplastics THV™ 200.

A general description and preparation of these classes of fluoropolymerscan be found in Encyclopedia Chemical Technology, FluorocarbonElastomers, Kirk-Othmer (1993), or in Modern Fluoropolymers, J. ScheirsEd, (1997), J Wiley Science, Chapters 2, 13, and 32. (ISBN0-471-97055-7).

In one embodiment, the fluoropolymers are copolymers formed from theconstituent monomers known as tetrafluoroethylene (“TFE”),hexafluoropropylene (“HFP”), and vinylidene fluoride (“VdF,” “VF2,”).The monomer structures for these constituents are shown below as (1),(2) and (3): TFE: CF 2=CF 2 (1); VDF: CH 2=CF 2 (2); HFP: CF 2=CF—CF 3(3)

In one embodiment, the preferred fluoropolymer consists of at least twoof the constituent monomers (HFP and VDF), and more preferably all threeof the constituents monomers in varying molar amounts. Additionalmonomers not depicted above but may also be useful in an embodimentinclude perfluorovinyl ether monomers of the general structure: CF2=CF—OR f, wherein R f can be a branched or linear perfluoroalkylradical of 1-8 carbons and can itself contain additional heteroatomssuch as oxygen. Specific examples are perfluoromethyl vinyl ether,perfluoropropyl vinyl ether, and perfluoro(3-methoxy-propyl) vinylether. Additional monomer examples are found in WO00/12754 to Worm,assigned to 3M, and U.S. Pat. No. 5,214,100 to Carlson. Otherfluoropolymer materials may be used such as those disclosed in U.S.patent application Ser. No. 11/026,614.

In one embodiment, the cladding material is birefringent and therefractive index in at least a first direction is less than refractiveindex of the lightguide region, lightguide core, or material to which itis optically coupled.

Collimated light propagating through a material may be reduced inintensity after passing through the material due to scattering(scattering loss coefficient), absorption (absorption coefficient), or acombination of scattering and absorption (attenuation coefficient). Inone embodiment, the cladding comprises a material with an averageabsorption coefficient for collimated light less than one selected fromthe group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and 0.005 cm⁻¹ over thevisible wavelength spectrum from 400 nanometers to 700 nanometers. Inanother embodiment, the cladding comprises a material with an averagescattering loss coefficient for collimated light less than one selectedfrom the group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and 0.005 cm⁻¹ over thevisible wavelength spectrum from 400 nanometers to 700 nanometers. Inanother embodiment, the cladding comprises a material with an averageattenuation coefficient for collimated light less than one selected fromthe group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and 0.005 cm⁻¹ over thevisible wavelength spectrum from 400 nanometers to 700 nanometers.

In a further embodiment, a lightguide comprises a hard cladding layerthat substantially protects a soft core layer (such as a soft siliconeor silicone elastomer).

In one embodiment, a lightguide comprises a core material with aDurometer Shore A hardness (JIS) less than 50 and at least one claddinglayer with a Durometer Shore A hardness (JIS) greater than 50. In oneembodiment, a lightguide comprises a core material with an ASTM D638—10Young's Modulus less than 2 MPa and at least one cladding layer with anASTM D638—10 Young's Modulus greater than 2 MPa at 25 degrees Celsius.In another embodiment, a lightguide comprises a core material with anASTM D638—10 Young's Modulus less than 1.5 MPa and at least one claddinglayer with an ASTM D638—10 Young's Modulus greater than 2 MPa at 25degrees Celsius. In a further embodiment, a lightguide comprises a corematerial with an ASTM D638—10 Young's Modulus less than 1 MPa and atleast one cladding layer with an ASTM D638—10 Young's Modulus greaterthan 2 MPa at 25 degrees Celsius.

In one embodiment, a lightguide comprises a core material with an ASTMD638—10 Young's Modulus less than 2 MPa and the lightguide film has anASTM D638—10 Young's Modulus greater than 2 MPa at 25 degrees Celsius.In another embodiment, a lightguide comprises a core material with anASTM D638—10 Young's Modulus less than 1.5 MPa and the lightguide filmhas an ASTM D638—10 Young's Modulus greater than 2 MPa at 25 degreesCelsius. In one embodiment, a lightguide comprises a core material withan ASTM D638—10 Young's Modulus less than 1 MPa and the lightguide filmhas an ASTM D638—10 Young's Modulus greater than 2 MPa at 25 degreesCelsius.

Reflective Elements

In one embodiment, at least one of the light source, light inputsurface, light input coupler, coupling lightguide, lightguide region,and lightguide comprises a reflective element or surface opticallycoupled to it, disposed adjacent to it, or disposed to receive lightfrom it wherein the reflective region is one selected from the group:specularly reflecting region, diffusely reflecting region, metalliccoating on a region (such as an ITO coating, Aluminized PET, Silvercoating, etc.), multi-layer reflector dichroic reflector, multi-layerpolymeric reflector, giant birefringent optical films, enhanced specularreflector films, reflective ink or particles within a coating or layer,and a white reflective film comprising at least one selected from thegroup: titanium dioxide, barium sulfate, and voids. In anotherembodiment, a light emitting device comprises a lightguide wherein atleast one light reflecting material selected from the group: a lightrecycling element, a specularly reflective tape with a diffusereflectance (specular component included) greater than 70%, aretroreflective film (such as a corner cube film or glass bead basedretroreflective film), white reflecting film, and aluminum housing isdisposed near or optically coupled at least one edge region of thelightguide disposed to receive light from the lightguide and redirect afirst portion of light back into the lightguide. In another embodiment,a light emitting device comprises a lightguide wherein at least onelight absorbing material selected from the group: a light absorbing tapewith a diffuse reflectance (specular component included) less than 50%,a region comprising a light absorbing dye or pigment, a regioncomprising carbon black particles, a region comprising light absorbingink, paint, films or surfaces, and a black material is disposed near oroptically coupled at least one edge region of the lightguide disposed toreceive light from the lightguide and redirect a first portion of lightback into the lightguide. In a further embodiment, a light reflectingmaterial and a light absorbing material of the aforementioned types isdisposed near or optically coupled at least one edge region of thelightguide disposed to receive light from the lightguide and redirect afirst portion of light back into the lightguide and absorb a secondportion of incident light. In one embodiment, the light reflecting orlight absorbing material is in the form of a line of ink or tape adheredonto the surface of the lightguide film. In one embodiment, the lightreflecting material is a specularly reflecting tape adhered to the topsurface, edge, and bottom surface of the lightguide near the edge of thelightguide. In another embodiment, the light absorbing material is alight absorbing tape adhered to the top surface, edge, and bottomsurface of the lightguide near the edge of the lightguide. In anotherembodiment, the light absorbing material is a light absorbing ink orpaint (such as a black acrylic based paint) adhered to at least oneselected from the group: edge, top surface near the edge, and bottomsurface near the edge of the lightguide film.

In one embodiment, the light emitting device is a backlight illuminatinga display or other object to be illuminated and the light emittingregion, lightguide, or lightguide region is disposed between areflective surface or element and the object to be illuminated. Inanother embodiment, the reflective element is a voided white PET filmsuch as TETORON® film UX Series from TEIJIN (Japan). In one embodiment,the reflective element or surface has a diffuse reflectance d/8 with thespecular component included (DR-SCI) measured with a Minolta CM508Dspectrometer greater than one selected from the group: 60%, 70%, 80%,90%, and 95%. In another embodiment, the reflective element or surfacehas a diffuse reflectance d/8 with the specular component excluded(DR-SCE) measured with a Minolta CM508D spectrometer greater than oneselected from the group: 60%, 70%, 80%, 90%, and 95%. In anotherembodiment, the reflective element or surface has a specular reflectancegreater than one selected from the group: 60%, 70%, 80%, 90%, and 95%.The specular reflectance, as defined herein, is the percentage of lightreflected from a surface illuminated by a 532 nanometer laser that iswithin a 10 degree (full angle) cone centered about the optical axis ofthe reflected light. This can be measured by using an integrating spherewherein the aperture opening for the integrating sphere is positioned ata distance from the point of reflection such that the angular extent ofthe captured light is 10 degrees full angle. The percent reflection ismeasured against a reflectance standard with a known specularreflectance, a reflectance standard, film, or object that have extremelylow levels of scattering.

Light Reflecting Optical Element is Also a Second Element

In addition to reflecting incident light, in one embodiment, the lightreflecting element is also at least one second element selected from thegroup: light blocking element, low contact area covering element,housing element, light collimating optical element, light turningoptical element and thermal transfer element. In another embodiment, thelight reflecting optical element is a second element within a region ofthe light reflecting optical element. In a further embodiment, the lightreflecting optical element comprises a bend region, tab region, holeregion, layer region, or extended region that is, or forms a componentthereof, a second element. For example, a diffuse light reflectingelement comprising a voided PET diffuse reflecting film may be disposedadjacent the lightguide region to provide diffuse reflection and thefilm may further comprise a specular reflecting metallized coating on anextended region of the film that is bent and functions to collimateincident light from the light source. In another embodiment, the secondelement or second region of the light reflecting optical element iscontiguous with one or more regions of the light reflecting opticalelement. In a further embodiment, the light reflecting optical elementis a region, coating, element or layer physically coupled to a secondelement. In another embodiment, the second element is a region, coating,element or layer physically coupled to a light reflecting opticalelement. For example, in one embodiment, the light reflecting opticalelement is a metalized PET film adhered to the back of a transparent,low contact area film comprising polyurethane and a surface reliefprofile wherein the film combination extends from beneath the lightguideregion to wrap around one or more coupling lightguides. In a furtherembodiment, the light reflecting optical element is physically and/oroptically coupled to the film-based lightguide and is cut during thesame cutting process that generates the coupling lightguides and thelight reflecting optical element is cut into regions that are angled,curved or subsequently angled or curved to form a light collimatingoptical element or a light turning optical element. The size, shape,quantity, orientation, material and location of the tab regions, lightreflecting regions or other regions of the light reflecting opticalelement may vary as needed to provide optical (efficiency, lightcollimation, light redirection, etc.), mechanical (rigidity, connectionwith other elements, alignment, ease of manufacture etc.), or system(reduced volume, increased efficiency, additional functionality such ascolor mixing) benefits such as is known in the art of optical elements,displays, light fixtures, etc. For example, the tab regions of a lightreflecting optical element that specularly reflects incident light maycomprise a parabolic, polynomial or other geometrical cross-sectionalshape such that the angular FWHM intensity, light flux, orientation,uniformity, or light profile is controlled. For example, the curvedcross-sectional shape of one or more tab regions may be that of acompound parabolic concentrator. In another embodiment, the lightreflecting optical element comprises hole regions, tab regions, adhesiveregions or other alignment, physical coupling, optical coupling, orpositioning regions that correspond in shape, size, or location to otherelements of the light emitting device to facilitate at least oneselected from the group: alignment, position, adhesion, physicallycoupling, or optically coupling with a second element or component ofthe light emitting device. For example, the light reflecting opticalelement may be a specularly reflecting or mirror-like metallized PETthat is disposed beneath a substantially planar light emitting regionand extends into the region near the light source and comprises extendedtabs or folding regions that fold and are optically coupled to at leastone outer surface of a light collimating element. In this embodiment,the light reflecting optical element is also a component of a lightcollimating optical element. In another embodiment, the light reflectingoptical element is a specularly reflecting metallized PET film that isoptically coupled to a non-folded coupling lightguide using a pressuresensitive adhesive and is extended toward the light source such that theextended region is optically coupled to an angled surface of a lightcollimating optical element that collimates a portion of the light fromthe light source in the plane perpendicular to the plane comprising thesurface of the non-folded coupling lightguide optically coupled to thelight reflecting optical element.

In one embodiment, the light reflecting element is also a light blockingelement wherein the light reflecting element blocks a first portion oflight escaping the light input coupler, coupling lightguide, lightsource, light redirecting optical element, light collimating opticalelement, light mixing region, lightguide region. In another embodiment,the light reflecting element prevents the visibility of stray light,undesirable light, or a predetermined area of light emitting orredirecting surface from reaching the viewer of a display, sign, or alight emitting device. For example, a metallized specularly reflectingPET film may be disposed to reflect light from one side of thelightguide region back toward the lightguide region and also extend towrap around the stack of coupling lightguide using the PSA opticallycoupled to the coupling lightguides (which may be a cladding layer forthe lightguides) to adhere the metallized PET film to the stack andblock stray light escaping from the coupling lightguides and becomingvisible.

In one embodiment, the light reflecting element is also a low contactarea covering. For example, in one embodiment, the light reflectingelement is a metallized PET film comprising a methacrylate based coatingthat comprises surface relief features. In this embodiment, the lightreflecting element may wrap around the stack without significantlyextracting light from the coupling lightguides when air is used as acladding region. In another embodiment, the reflective element hasnon-planar regions such that the reflective surface is not flat and thecontact area between the light reflecting film and one or more couplinglightguides or lightguide regions is a low percentage of the exposedsurface area.

In another embodiment, the light reflecting element is also a housingelement. For example, in one embodiment, the light reflecting element isa reflective coating on the inner wall of the housing for the couplinglightguides. The housing may have reflective surfaces or reflect lightfrom within (such as an internal reflecting layer or material). Thelight reflecting element may be the housing for the lightguide region orother lightguide or component of the light emitting device.

In a further embodiment, the light reflecting element is also a lightcollimating optical element disposed to reduce the angular full-width athalf maximum intensity of light from a light source before the lightenters one or more coupling lightguides. In one embodiment, the lightreflecting optical element is a specularly reflecting multilayerpolymeric film (such as a giant birefringent optical film) disposed onone side of the light emitting region of lightguide film and extended ina direction toward the light source with folds or curved regions thatare bent or folded to form angled or curved shapes that receive lightfrom the light source and reflect and collimate light toward the inputsurface of one or more coupling lightguides. More than one fold orcurved region may be used to provide different shapes or orientations oflight reflecting surfaces for different regions disposed to receivelight from the light source. For example, an enhanced specularlyreflecting multilayer polymer film (such as a giant birefringent opticalfilm) disposed and optically coupled to the lightguide region of afilm-based lightguide using a low refractive index PSA cladding layermay extend toward the light source and comprise a first extended regionthat wraps around the cladding region to protect and block stray lightand further comprise an extended region that comprises two tabs that arefolded and a cavity wherein the light source may be disposed such thatlight from the light source within a first plane is collimated by theextended region tabs. In one embodiment, the use of the light reflectingelement that is physically coupled to another component in the lightemitting device (such as the film-based lightguide or couplinglightguides) provides an anchor or registration assistance for aligningthe light collimating optical element tabs or reflective regions of thelight reflecting element.

In a further embodiment, the light reflecting element is also a lightturning optical element disposed to redirect the optical axis of lightin a first plane. In one embodiment, the light reflecting opticalelement is a specularly reflecting multilayer polymer film (such as agiant birefringent optical film) disposed on one side of the lightemitting region of lightguide film and extended in a direction towardthe light source with folds or curved regions that are bent or folded toform angled or curved shapes that receive light from the light sourceand reflect and redirect the optical axis of the incident light towardthe input surface of one or more coupling lightguides. More than onefold or curved region may be used to provide different shapes ororientations of light reflecting surfaces for different regions disposedto receive light from the light source. For example, a specularlyreflecting multilayer polymer film disposed and optically coupled to thelightguide region of a film-based lightguide using a low refractiveindex PSA cladding layer may extend toward the light source and comprisean first extended region that wraps around the cladding region toprotect and block stray light and further comprise an extended regionthat comprises two tabs that are folded and a cavity wherein the lightsource may be disposed such that optical axis of the light from thelight source within a first plane in a first direction is redirected bythe extended region tabs into a second direction different than thefirst direction. In one embodiment, the use of the light reflectingelement that is physically coupled to another component in the lightemitting device (such as the film-based lightguide or couplinglightguides) provides an anchor or registration assistance for aligningthe light turning optical element tabs or reflective regions of thelight reflecting element.

In a further embodiment, the light reflecting element is also a thermaltransfer element that transfers heat away from the light source. Forexample, in one embodiment, the light reflecting element is a reflectivealuminum housing disposed on one side of the lightguide region andextending to and thermally coupled to a circuit board that is thermallycoupled to the light source such that heat from the light source isthermally transferred to the aluminum. In another example, the lightreflecting optical element is a high reflectance polished region of analuminum sheet that further comprises (or is thermally coupled to) anextrusion region with fins or heat sink extensions. In anotherembodiment, the thermal transfer element is an aluminum extrusioncomprising the coupling lightguide in an interior region wherein theinner surface of the extrusion is a light reflecting optical elementdisposed to reflect light received from the coupling lightguides backtoward the coupling lightguides. In another embodiment, the thermaltransfer element is an aluminum extrusion comprising couplinglightguides in an interior region wherein the extrusion furthercomprises a light collimating reflective surface disposed to collimatelight from the light source.

Protective Layers

In one embodiment, at least one selected from the group: light inputsurface, light input coupler, coupling lightguide, lightguide region,and lightguide comprises a protective element or layer optically coupledto it, physically coupled to it, disposed adjacent to it, or disposedbetween it and a light emitting surface of the light emitting device. Aprotective film element can have a higher scratch resistance, higherimpact resistance, hardcoating layer, impact absorbing layer or otherlayer or element suitable to protect at least one selected from thegroup: light input surface, light input coupler, coupling lightguide,lightguide region, and lightguide from scratches, impacts, dropping thedevice, and interaction with sharp objects, etc.

Coupling Light into the Surface of the Coupling Lightguide

In one embodiment, the light input surface of the light input coupler isat least one surface of at least one coupling lightguide. In oneembodiment, light is coupled into a coupling lightguide such that itremains in the lightguide for multiple total internal reflections by atleast one optical element or feature on at least one surface oroptically coupled to at least one surface comprising an optical regionselected from the group: lens, prismatic lens, prismatic film,diffraction grating, holographic optical element, diffractive opticalelement, diffuser, anisotropic diffuser, refractive surface relieffeatures, diffractive surface relief features, volumetric lightre-directing features, micro-scale volumetric or surface relieffeatures, nano-scale volumetric or surface relief features, andtotal-internal-reflection volumetric or surface features. The opticalelement or feature may be incorporated on one or several couplinglightguides in a stacked or predetermined physically arrangeddistribution of coupling lightguides. In one embodiment, the opticalelement or feature is arranged spatially in a pattern within or on onecoupling lightguide or across multiple coupling lightguides. In oneembodiment, the coupling efficiency of an optical element or feature isgreater than one selected from the group: 50%, 60%, 70%, 80%, and 90%for a wavelength range selected from one selected from the group: 350nm-400 nm, 400 nm-700 nm, 450 nm-490 nm, 490 nm-560 nm, and 635 nm-700nm. The coupling efficiency as defined herein is the percent of incidentlight from a light source disposed to direct light onto at least onecoupling lightguide which is coupled into the at least one couplinglightguide disposed to receive light from the light source which remainswithin the coupling lightguide at an angle greater than the criticalangle further along in the region of the lightguide just past the lightinput surface region. In one embodiment, two or more couplinglightguides are stacked or bundled together wherein they each have anoptical element or feature disposed to couple light into the couplinglightguide and the optical element or feature has a coupling efficiencyless than one selected from the group: 50%, 60%, 70%, 80%, and 90% for awavelength range selected from one selected from the group: 350 nm-400nm, 400 nm-700 nm, 450 nm-490 nm, 490 nm-560 nm, and 635 nm-700 nm. Bystacking a group of coupling lightguides, for example, one can use lowercoupling efficiencies to enable a portion of the incident light to passthrough a first coupling lightguide onto a second coupling lightguide toallow light to be coupled into the second coupling lightguide. In oneembodiment, the coupling efficiency is graded or varies in a firstdirection through an arrangement of coupling lightguides and a lightreflecting element or region is disposed on the opposite side of thearrangement of coupling lightguides disposed to reflect a portion ofincident light back through the coupling lightguides.

Coupling Light into Two or More Surfaces

In one embodiment, light is coupled through light input couplers,coupling lightguides, optical elements, or a combination thereof to atleast two surfaces or surface regions of a at least one lightguide in alight emitting device. In another embodiment, the light coupled throughthe surface of a lightguide or lightguide region is directed by thelight extraction features into an angular range different than that ofthe light directed by the same or different light extraction featuresfrom light coupled through a second surface or second surface region ofa lightguide or lightguide region of a light emitting device. In anotherembodiment, a first light extracting region comprising a first set oflight re-directing features or light extraction features that directslight incident through a first surface or edge into a first range ofangles upon exiting the light emitting surface of the lightguide and asecond light extracting region comprises a second set of lightre-directing or light extraction features that direct light incidentthrough a second surface or edge into a second range of angles uponexiting the light emitting surface of the lightguide. Variations in thelight re-directing features include, but are not limited to, featureheight, shape, orientation, density, width, length, material, angle of asurface, location in the x, y, and z direction and include dispersedphase domains, grooves, pits, micro-lenses, prismatic elements, aircavities, hollow microspheres, dispersed microspheres, and other knownlight extraction features or elements. In another embodiment, a lightemitting device comprises at least one lightguide and a first lightsource disposed to couple light through a surface of at least onelightguide and a second light source disposed to couple light throughthe edge of at least one lightguide wherein the coupling mechanism is atleast one selected from the group: light input couplers, opticalelement, coupling lightguide, optical components or coupling lightguidesoptically coupled to a surface or edge, diffractive optics, holographicoptical element, diffraction grating, Fresnel lens element, prismaticfilm, light redirecting optic, and other optical element.

Light Input Couplers Disposed Near More than One Edge of a Lightguide

In one embodiment, a light emitting device comprises a plurality oflight input couplers disposed to couple light into a lightguide from atleast two input regions disposed near two different edges of alightguide. In another embodiment, two light input couplers are disposedon opposite sides of a lightguide. In another embodiment, light inputcouplers are disposed on three or four sides of a film-type lightguide.In a further embodiment, more than one light input coupler, housing, orlight input surface is disposed to receive light from a single lightsource, light source package, array of light sources or light sourcestrip (such as a substantially linear array of LEDs). For example, twohousing for two light input couplers disposed to couple light to twodifferent regions of a lightguide are disposed to receive light from asubstantially linear array of LEDs. In another embodiment a first inputsurface comprising a first collection of coupling lightguides opticallycoupled to a first region of a lightguide and a second input surfacecomprising a second collection of coupling lightguides optically coupledto a second region of a lightguide different than the first region aredisposed to receive light from one selected from the group: the samelight source, a plurality of light sources, light sources in a package,an array or collection of light sources, a linear array of lightsources, one or more LEDs, an LED package, a linear array of LEDs, andLEDs of multiple colors.

Strip Folding Device

In one embodiment, the light emitting device comprises frame memberswhich assist in at least one of the folding or holding of the couplinglightguides or strips. Methods for folding and holding couplinglightguides such as film-based lightguides using frame members aredisclosed in International (PCT) Publication No. WO 2009/048863 and PCTapplication entitled “Illumination via flexible thin films” filed onJan. 26, 2010 by Anthony Nichols and Shawn Pucylowski, U.S. Provisionalpatent application Ser. Nos. 61/147,215 and 61/147,237. In oneembodiment, the coupling lightguide folding (or bending) and/or holding(or housing) element is formed from at least one selected from thegroup: rigid plastic material, black colored material, opaque material,semi-transparent material, metal foil, metal sheet, aluminum sheet, andaluminum foil. In one embodiment, the folding or holding material has aflexural rigidity or (flexural modulus) at least twice the flexuralrigidity (or modulus) of the film or coupling lightguides which it foldsor holds.

Housing or Holding Device for Light Input Coupler

In one embodiment, a light emitting device comprises a housing orholding device that holds or contains at least part of a light inputcoupler and light source. The housing or holding device may house orcontain within at least one selected from the group: light inputcoupler, light source, coupling lightguides, lightguide, opticalcomponents, electrical components, heat sink or other thermalcomponents, attachment mechanisms, registration mechanisms, foldingmechanisms devices, and frames. The housing or holding device maycomprise a plurality of components or any combination of theaforementioned components. The housing or holding device may serve oneor more of functions selected from the group: protect from dust anddebris contamination, provide air-tight seal, provide a water-tightseal, house or contain components, provide a safety housing forelectrical or optical components, assist with the folding or bending ofthe coupling lightguides, assist in the alignment or holding of thelightguide, coupling lightguide, light source or light input couplerrelative to another component, maintain the arrangement of the couplinglightguides, recycle light (such as with reflecting inner walls),provide attachment mechanisms for attaching the light emitting device toan external object or surface, provide an opaque container such thatstray light does not escape through specific regions, provide atranslucent surface for displaying indicia or providing illumination toan object external to the light emitting device, comprise a connectorfor release and interchangeability of components, and provide a latch orconnector to connect with other holding devices or housings.

In one embodiment, the coupling lightguides are terminated within thehousing or holding element. In another embodiment, the inner surface ofthe housing or holding element has a specular or diffuse reflectancegreater than 50% and the inner surface appears white or mirror-like. Inanother embodiment, the outer surface of the housing or holding devicehas a specular or diffuse reflectance greater than 50% and the outersurface appears white or mirror-like. In another embodiment, at leastone wall of the housing or holding device has a specular or diffusereflectance less than 50% and the inner surface appears gray, black orlike a very dark mirror. In another embodiment, at least one wall orsurface of the housing or holding device is opaque and has a luminoustransmittance measured according to ASTM D1003 of less than 50%. Inanother embodiment, at least one wall or surface of the housing orholding device has a luminous transmittance measured according to ASTMD1003 greater than 30% and the light exiting the wall or surface fromthe light source within the housing or holding device providesillumination for a component of the light emitting device, illuminationfor an object external to the light emitting device, or illumination ofa surface to display a sign, indicia, passive display, a second displayor indicia, or an active display such as providing backlightillumination for an LCD.

In one embodiment, the housing or holding device comprises at least oneselected from the group: connector, pin, clip, latch, adhesive region,clamp, joining mechanism, and other connecting element or mechanicalmeans to connect or hold the housing or holding device to one or moreselected from the group: another housing or holding device, lightguide,coupling lightguide, film, strip, cartridge, removable component orcomponents, an exterior surface such as a window or automobile, lightsource, electronics or electrical component, the circuit board for theelectronics or light source such as an LED, heat sink or other thermalcontrol element, frame of the light emitting device, and other componentof the light emitting device.

In another embodiment, the input ends and output ends of the couplinglightguides are held in physical contact with the relative positionmaintaining elements by at least one selected from the group: magneticgrips, mechanical grips, clamps, screws, mechanical adhesion, chemicaladhesion, dispersive adhesion, diffusive adhesion, electrostaticadhesion, vacuum holding, or an adhesive.

Curved or Flexible Housing

In another embodiment, the housing comprises at least one curvedsurface. A curved surface can permit non-linear shapes or devices orfacilitate incorporating non-planer or bent lightguides or couplinglightguides. In one embodiment, a light emitting device comprises ahousing with at least one curved surface wherein the housing comprisescurved or bent coupling lightguides. In another embodiment, the housingis flexible such that it may be bent temporarily, permanently orsemi-permanently. By using a flexible housing, for example, the lightemitting device may be able to be bent such that the light emittingsurface is curved along with the housing, the light emitting area maycurve around a bend in a wall or corner, for example. In one embodiment,the housing or lightguide may be bent temporarily such that the initialshape is substantially restored (bending a long housing to get itthrough a door for example). In another embodiment, the housing orlightguide may be bent permanently or semi-permanently such that thebent shape is substantially sustained after release (such as when it isdesired to have a curved light emitting device to provide a curved signor display, for example).

Housing Including a Thermal Transfer Element

In one embodiment, the housing comprises a thermal transfer elementdisposed to transfer heat from a component within the housing to anouter surface of the housing. In another embodiment, the thermaltransfer element is one selected from the group: heat sink, metallic orceramic element, fan, heat pipe, synthetic jet, air j et producingactuator, active cooling element, passive cooling element, rear portionof a metal core or other conductive circuit board, thermally conductiveadhesive, or other component known to thermally conduct heat. In oneembodiment, the thermal transfer element has a thermal conductivity(W/(m·K)) greater than one selected from the group: 0.2, 0.5, 0.7, 1, 3,5, 50, 100, 120, 180, 237, 300, and 400.

Size of the Housing or Coupling Lightguide Holding Device

In one embodiment, the sizes of the two smaller dimensions of thehousing or coupling lightguide holding device are less than one selectedfrom the group: 500, 400, 300, 200, 100, 50, 25, 10, and 5 times thethickness of the lightguide or coupling lightguides. In anotherembodiment, at least one dimension of the housing or lightguide holdingdevice is smaller due to the use of more than one light input couplerdisposed along an edge of the lightguide. In this embodiment, thethickness of the housing or holding device can be reduced because for afixed number of strips or coupling lightguides, they can be arrangedinto multiple smaller stacks instead of a single larger stack. This alsoenables more light to be coupled into the lightguide by using multiplelight input couplers and light sources.

Low Contact Area Cover

In one embodiment, a low contact area cover is disposed between at leastone coupling lightguide and the exterior to the light emitting device.The low contact area cover or wrap provides a low surface area ofcontact with a region of the lightguide or a coupling lightguide and mayfurther provide at least one selected from the group: protection fromfingerprints, protection from dust or air contaminants, protection frommoisture, protection from internal or external objects that woulddecouple or absorb more light than the low contact area cover when incontact in one or more regions with one or more coupling lightguides,provide a means for holding or containing at least one couplinglightguide, hold the relative position of one or more couplinglightguides, and prevent the coupling lightguides from unfolding into alarger volume or contact with a surface that could de-couple or absorblight.

In another embodiment, the low contact area cover is disposed betweenthe outer surface of the light emitting device and the regions of thecoupling lightguides disposed between the fold or bend region and thelightguide or light mixing region. In a further embodiment, the lowcontact area cover is disposed between the outer surface of the lightemitting device and the regions of the coupling lightguides disposedbetween the light input surface of the coupling lightguides and thelightguide or light mixing region. In another embodiment, the lowcontact area cover is disposed between the outer surface of the lightemitting device and a portion of the regions of the coupling lightguidesnot enclosed by a housing, protective cover, or other component disposedbetween the coupling lightguides and the outer surface of the lightemitting device. In one embodiment, the low contact area cover is thehousing, relative position maintaining element, or a portion of thehousing or relative positioning maintaining element.

Film-Based Low Contact Area Cover

In one embodiment the low contact area cover is a film with at least oneof a lower refractive index than the refractive index of the outermaterial of the coupling lightguide disposed near the low contact areacover, and a surface relief pattern or structure on the surface of thefilm-based low contact area cover disposed near at least one couplinglightguide. In one embodiment, the low contact area comprises convex orprotruding surface relief features disposed near at least one outersurface of at least one coupling lightguide and the average percentageof the area disposed adjacent to an outer surface of a couplinglightguide or the lightguide that is in physical contact with thesurface relief features is less than one of the following: 70%, 50%,30%, 10%, 5%, and 1%. In one embodiment, a convex surface relief profiledesigned to have a low contact area with a surface of the couplinglightguide will at least one selected from the group: extract, absorb,scatter, or otherwise alter the intensity or direction of a lowerpercentage of light propagating within the coupling lightguide than aflat surface of the same material. In one embodiment, the surface reliefprofile is at least one selected from the group: random, semi-random,ordered, regular in one or 2 directions, holographic, tailored, comprisecones, truncated polyhedrons, truncated hemispheres, truncated cones,truncated pyramids, pyramids, prisms, pointed shapes, round tippedshapes, rods, cylinders, hemispheres, and other geometrical shapes. Inone embodiment, the low contact area cover material or film is at leastone selected from the group: transparent, translucent, opaque, lightabsorbing, light reflecting, substantially black, substantially white,has a diffuse reflectance specular component included greater than 70%,has a diffuse reflectance specular component included less than 70%, hasan ASTM D1003 luminous transmittance less than 30%, has an ASTM D1003luminous transmittance greater than 30%, absorbs at least 50% of theincident light, absorbs less than 50% of the incident light, has anelectrical sheet resistance less than 10 ohms per square, and have anelectrical sheet resistance greater than 10 ohms per square.

In another embodiment, the low contact area cover is a film with athickness less than one selected from the group: 600 microns, 500microns, 400 microns, 300 microns, 200 microns, 100 microns, and 50microns.

Wrap Around Low Contact Area Cover

In a further embodiment, the low contact area cover is the inner surfaceor physically coupled to a surface of a housing, holding device, orrelative position maintaining element. In a further embodiment, the lowcontact area cover is a film which wraps around at least one couplinglightguide such that at least one lateral edge and at least one lateralsurface is substantially covered such that the low contact area cover isdisposed between the coupling lightguide and the outer surface of thedevice.

In another embodiment, a film-based lightguide comprises a low contactarea cover wrapped around a first group of coupling lightguides whereinthe low contact area cover is physically coupled to at least oneselected from the group: lightguide, lightguide film, light inputcoupler, lightguide, housing, and thermal transfer element by a lowcontact area cover physical coupling mechanism. In another embodiment,the light emitting device comprises a first cylindrical tension roddisposed to apply tension to the low contact area cover film and holdthe coupling lightguides close together and close to the lightguide suchthat the light input coupler has a lower profile. In another embodiment,the low contact area cover can be pulled taught after physicallycoupling to at least one selected from the group: lightguide, lightguidefilm, light input coupler, lightguide, housing, thermal transferelement, and other element or housing by moving the first cylindricaltension rod away from a second tension bar or away from a physicalcoupling point of the mechanism holding the tension bar such as a brace.Other shapes and forms for the tension forming element may be used suchas a rod with a rectangular cross-section, a hemisphericalcross-section, or other element longer in a first direction capable ofproviding tension when translated or supporting tension when heldstationary relative to other components. In another embodiment, a firstcylindrical tension rod may be translated in a first direction toprovide tension while remaining in a brace region and the position ofthe cylindrical tension rod may be locked or forced to remain in placeby tightening a screw for example. In another embodiment, the tensionforming element and the brace or physical coupling mechanism forcoupling it to another component of the light input coupler does notextend more than one selected from the group: 1 millimeter, 2millimeters, 3 millimeters, 5 millimeters, 7 millimeters and 10millimeters past at least one edge of the lightguide in the directionparallel to the longer dimension of the tension forming element.

Low Hardness Low Contact Area Cover

In another embodiment, the low contact area cover has an ASTM D3363pencil hardness under force from a 300 gram weight less than the outersurface region of the coupling lightguide disposed near the low contactarea cover. In one embodiment, the low contact area cover comprises asilicone, polyurethane, rubber, or thermoplastic polyurethane with asurface relief pattern or structure. In a further embodiment, the ASTMD3363 pencil hardness under force from a 300 gram weight of the lowcontact area cover is at least 2 grades less than the outer surfaceregion of the coupling lightguide disposed near the low contact areacover.

Physical Coupling Mechanism for Low Contact Area Cover

In one embodiment, the low contact area cover is physically coupled in afirst contact region to the light emitting device, light input coupler,lightguide, housing, second region of the low contact area cover, orthermal transfer element by one or more methods selected from the group:sewing (or threading or feeding a fiber, wire, or thread) the lowcontact area cover to the lightguide, light mixing region, or othercomponent, welding (sonic, laser, thermo-mechanically, etc.) the lowcontact area cover to one or more components, adhering (epoxy, glue,pressure sensitive adhesive, etc.) the low contact area cover to one ormore components, fastening the low contact area cover to one or morecomponents. In a further embodiment, the fastening mechanism is selectedfrom the group: a batten, button, clamp, clasp, clip, clutch (pinfastener), flange, grommet, anchor, nail, pin, peg, clevis pin, cotterpin, linchpin, R-clip, retaining ring, circlip retaining ring, e-ringretaining ring, rivet, screw anchor, snap, staple, stitch, strap, tack,threaded fastener, captive threaded fasteners (nut, screw, stud,threaded insert, threaded rod), tie, toggle, hook-and-loop strips, wedgeanchor, and zipper.

In another embodiment, the physical coupling mechanism maintains theflexibility of at least selected from the group: light emitting device,lightguide and coupling lightguides. In a further embodiment, the totalsurface area of the physical coupling mechanism in contact with at leastone selected from the group: low contact area cover, couplinglightguides, lightguide region, light mixing region, and light emittingdevice is less than one selected from the group: 70%, 50%, 30%, 10%, 5%,and 1%. In another embodiment, the total percentage of the crosssectional area of the layers comprising light propagating under totalinternal reflection comprising the largest component of the low contactarea cover physical coupling mechanism in a first directionperpendicular to the optical axis of the light within the couplinglightguides, light mixing region or lightguide region relative to thecross-sectional area in the first direction is less than one selectedfrom the group: 10%, 5%, 1%, 0.5%, 0.1%, and 0.05%. For example, in oneembodiment, the low contact area cover is a flexible transparentpolyurethane film with a surface comprising a regular two-dimensionalarray of embossed hemispheres disposed adjacent and wrapping around thestack of coupling lightguides and is physically coupled to the lightmixing region of the lightguide comprising a 25 micron thick core layerby threading the film to the light mixing region using a transparentnylon fiber with a diameter less than 25 microns into 25 micron holes at1 centimeter intervals. In this example, the largest component of thephysical coupling mechanism is the holes in the core region which canscatter light out of the lightguide. Therefore, the aforementionedcross-sectional area of the physical coupling mechanism (the holes inthe core layer) is 0.25% of the cross-sectional area of the core layer.In another embodiment, the fiber or material threaded through the holesin one or more components comprises at least one selected from thegroup: polymer fiber, polyester fiber, rubber fiber, cable, wire (suchas a thin steel wire), aluminum wire, and nylon fiber such as used infishing line. In a further embodiment, the diameter of the fiber ormaterial threaded through the holes is less than one selected from thegroup: 500 microns, 300 microns, 200 microns, 100 microns, 50 microns,25 microns, and 10 microns. In another embodiment, the fiber or threadedmaterial is substantially transparent or translucent.

In another embodiment, the physical coupling mechanism for the lowcontact area cover comprises holes within lightguide through which anadhesive, epoxy or other adhering material is deposited which bonds tothe low contact area cover. In another embodiment, the adhesive, epoxy,or other adhering material bonds to the low contact area cover and atleast one selected from the group: core region, cladding region, andlightguide. In another embodiment, the adhesive material has arefractive index greater than 1.48 and reduces the scatter out of thelightguide from the hole region over using an air gap or an air gap witha fiber, thread, or wire through the hole. In a further embodiment, anadhesive is applied as a coating on the fiber (which may be UVactivated, cured, etc. after threading, for example) or an adhesive isapplied to the fiber in the region of the hole such that the adhesivewicks into the hole to provide reduced scattering by at least oneselected from the group: optically coupling the inner surfaces of thehole, and optically coupling the fiber to the inner surfaces of thehole.

The physical coupling mechanism in one embodiment may be used tophysically couple together one or more elements selected from the group:film-based lightguide, low contact area cover film, housing, relativeposition maintaining element, light redirecting element or film,diffuser film, collimation film, light extracting film, protective film,touchscreen film, thermal transfer element, and other film or componentwithin the light emitting device.

Lightguide Configuration and Properties

The use of plastic film with thickness less than 0.5 mm for edge litlightguides can hold many advantages over using plastic plate or sheets.A flexible film may be able to be shaped to surfaces, be folded up forstorage, change shape as needed, or wave in the air. Another advantagemay be lower cost. The reduction in thickness helps reduce the cost formaterial, fabrication, storage and shipping for a lightguide of a givenwidth and length. Another reason may be that the decreased thicknessmakes it able to be added to surfaces without appreciable change in thesurface's shape, thickness and or appearance. For example, it can beadded to the surface of a window easily without changing the look of thewindow. Another advantage may be that the film or lightguide can berolled up. This helps in transportability, can hold some functionality,and may be particularly useful for hand-held devices where a roll-outscreen is used. A fifth reason is that the film can weigh less, whichagain makes it easier to handle and transport, A sixth reason may bethat film is commonly extruded in large rolls so larger edge-lit signagecan be produced. Finally, a seventh reason may be that there are manycompanies set up to coat, cut, laminate and manipulate film since filmis useful for many other industries. Plastic films are made by blown orcast-extrusion in widths up to 6.096 meters or longer and in rollsthousands of meters long. Co-extrusion of different materials from twoto 100 layers can be achieved with special extrusion dies.

Thickness of the Film or Lightguide

In one embodiment, the thickness of the film, lightguide or lightguideregion is within a range of 0.005 mm to 0.5 mm. In another embodiment,the thickness of the film or lightguide is within a range of 0.025millimeters to 0.5 millimeters. In a further embodiment, the thicknessof the film, lightguide or lightguide region is within a range of 0.050millimeters to 0.175 millimeters. In one embodiment, the thickness ofthe film, lightguide or lightguide region is less than 0.2 millimetersor less than 0.5 millimeters. In one embodiment, the average thicknessof the lightguide or core region is less than one selected from thegroup: 150 microns, 100 microns, 60 microns, 30 microns, 20 microns, 10microns, 6 microns, and 4 microns. In one embodiment, at least oneselected from the group: thickness, largest thickness, averagethickness, greater than 90% of the entire thickness of one or moreselected from the group: film, lightguide, and lightguide region is lessthan 0.2 millimeters. In another embodiment, the size to thicknessratio, defined as the largest dimension of the light emitting region inthe plane of the light emitting region divided by the average thicknesswithin the light emitting region is greater than one selected from thegroup: 100; 500; 1,000; 3,000; 5,000; 10,000; 15,000; 20,000; 30,000;and 50,000.

Optical Properties of the Lightguide or Light Transmitting Material

With regards to the optical properties of lightguides or lighttransmitting materials for embodiments, the optical properties specifiedherein may be general properties of the lightguide, the core, thecladding, or a combination thereof or they may correspond to a specificregion (such as a light emitting region, light mixing region, or lightextracting region), surface (light input surface, diffuse surface, flatsurface), and direction (such as measured normal to the surface ormeasured in the direction of light propagation through the lightguide).In one embodiment, the average luminous transmittance of the lightguidemeasured within at least one selected from the group: light emittingregion, light mixing region, and lightguide according to ASTM D1003 witha BYK Gardner haze meter is greater than one selected from the group:70%, 80%, 88%, 92%, 94%, 96%, 98%, and 99%. In another embodiment, theaverage luminous transmittance of the lightguide measured within themajor light emitting area (the area comprising greater than 80% of thetotal light emitted from the lightguide) according to ASTM D1003 with aBYK Gardner haze meter is greater than one selected from the group: 70%,80%, 88%, 92%, 94%, 96%, 98%, and 99%.

In another embodiment, the average haze of the lightguide measuredwithin at least one selected from the group: light emitting region,light mixing region, and lightguide measured with a BYK Gardner hazemeter is less than one selected from the group: 70%, 60%, 50%, 40%, 30%,20%, 10%, 5% and 3%. In another embodiment, the average clarity of thelightguide measured within at least one selected from the group: lightemitting region, light mixing region, and lightguide according to themeasurement procedure associated with ASTM D1003 with a BYK Gardner hazemeter is greater than one selected from the group: 70%, 80%, 88%, 92%,94%, 96%, 98%, and 99%.

In a further embodiment, the diffuse reflectance of the lightguidemeasured within at least one selected from the group: light emittingregion, light mixing region, and lightguide using a Minolta CM-508dspectrophotometer is less than one selected from the group: 30%, 20%,10%, 7%, 5%, and 2% with the spectral component included or with thespectral component excluded when placed above a light absorbing 6″×6″×6″box comprising Light Absorbing Black-Out Material from Edmund Optics onthe inner walls. In another embodiment, the diffuse reflectance of thelightguide measured within the major light emitting area (the areacomprising greater than 80% of the total light emitted from thelightguide) using a Minolta CM-508d spectrophotometer is less than oneselected from the group: 30%, 20%, 10%, 7%, 5%, and 2% with the spectralcomponent included or with the spectral component excluded when placedabove a light absorbing 6″×6″×6″ box comprising Light AbsorbingBlack-Out Material from Edmund Optics Inc. on the inner walls.

In another embodiment, the average clarity of the lightguide measuredwithin at least one selected from the group: light emitting region,light mixing region, and lightguide measured with a BYK Gardner hazemeter is greater than one selected from the group: 70%, 80%, 88%, 92%,94%, 96%, 98%, and 99%.

Factors which can determine the transmission of light through the film(in the thickness direction) include inherent material absorption,refractive index (light loss due to Fresnel reflections), scattering(refraction, reflection, or diffraction) from particles or featureswithin the volume or on a surface or interface (size, shape, spacing,total number of particles or density in two orthogonal directionsparallel to the film plane and the plane orthogonal to the film),absorption/scattering/reflection/refraction due to other materials(additional layers, claddings, adhesives, etc.), anti-reflectioncoatings, surface relief features.

In one embodiment, the use of a thin film for the lightguide permits thereduction in size of light extraction features because more waveguidemodes will reach the light extraction feature when the thickness of thefilm is reduced. In a thin lightguide, the overlap of modes is increasedwhen the thickness of the waveguide is reduced.

In one embodiment, the film-based lightguide has a graded refractiveindex profile in the thickness direction. In another embodiment, thethickness of the lightguide region or lightguide is less than 10 micronsand the lightguide is a single mode lightguide.

In one embodiment, the light transmitting material used in at least oneselected from the group: coupling lightguide, lightguide, lightguideregion, optical element, optical film, core layer, cladding layer, andoptical adhesive has an optical absorption (dB/km) less than oneselected from the group: 50, 100, 200, 300, 400, and 500 dB/km for awavelength range of interest. The optical absorption value may be forall of the wavelengths throughout the range of interest or an averagevalue throughout the wavelengths of interest. The wavelength range ofinterest for high transmission through the light transmitting materialmay cover the light source output spectrum, the light emitting deviceoutput spectrum, optical functionality requirements (IR transmission forcameras, motion detectors, etc., for example), or some combinationthereof. The wavelength range of interest may be a wavelength rangeselected from the group: 400 nm-700 nm, 300 nm-800 nm, 300 nm-1200 nm,300 nm-350 nm, 300-450 nm, 350 nm-400 nm, 400 nm-450 nm, 450 nm-490 nm,490 nm-560 nm, 500 nm-550 nm, 550 nm-600 nm, 600 nm-650 nm, 635 nm-700nm, 650 nm-700 nm, 700 nm-750 nm, 750 nm-800 nm, and 800 nm-1200 nm.

Collimated light propagating through light transmitting material may bereduced in intensity after passing through the material due toscattering (scattering loss coefficient), absorption (absorptioncoefficient), or a combination of scattering and absorption (attenuationcoefficient). In one embodiment, the core material of the lightguide hasan average absorption coefficient for collimated light less than oneselected from the group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and 0.005 cm⁻¹over the visible wavelength spectrum from 400 nanometers to 700nanometers. In another embodiment, the core material of the lightguidehas an average scattering loss coefficient for collimated light lessthan one selected from the group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and0.005 cm⁻¹ over the visible wavelength spectrum from 400 nanometers to700 nanometers. In one embodiment, the core material of the lightguidehas an average attenuation coefficient for collimated light less thanone selected from the group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹, and 0.005cm⁻¹ over the visible wavelength spectrum from 400 nanometers to 700nanometers. In another embodiment, the lightguide is disposed to receiveinfrared light and the average of at least one selected from the group:absorption coefficient, scattering loss coefficient, and attenuationcoefficient of the core layer or cladding layer for collimated light isless than one selected from the group: 0.03 cm⁻¹, 0.02 cm⁻¹, 0.01 cm⁻¹,and 0.005 cm⁻¹ over the wavelength spectrum from 700 nanometers to 900nanometers.

In one embodiment, the lightguide has a low absorption in the UV andblue region and the lightguide further comprises a phosphor film orwavelength conversion element. By using a blue or UV light source and awavelength conversion element near the output surface of the lightguidefor generation of white light, the light transmitting material can beoptimized for very high blue or UV light transmission. This can increasethe range of materials suitable for lightguides to include those thathave high absorption coefficients in the green and red wavelengthregions for example.

In another embodiment, the lightguide is the substrate for a displaytechnology. Various high-performance films are known in the displayindustry as having sufficient mechanical and optical properties. Theseinclude, but are not limited to polycarbonate, PET, PMMA, PEN, COC, PSU,PFA, FEP, and films made from blends and multilayer components. In oneembodiment, the light extraction feature is formed in a lightguideregion of a film before or after the film is utilized as a substrate forthe production or use as a substrate for a display such as an OLEDdisplay, MEMs based display, polymer film-based display, bi-stabledisplay, electrophoretic display, electrochromic display,electro-optical display, passive matrix display, or other display thatcan be produced using polymer substrates.

Refractive Index of the Light Transmitting Material

In one embodiment, the core material of the lightguide has a highrefractive index and the cladding material has a low refractive index.In one embodiment, the core is formed from a material with a refractiveindex (n_(D)) greater than one selected from the group: 1.3, 1.4, 1.5,1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9,and 3.0. In another embodiment, the refractive index (n_(D)) of thecladding material is less than one selected from the group: 1.1, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5.

The core or the cladding or other light transmitting material usedwithin an embodiment may be a thermoplastic, thermoset, rubber, polymer,silicone or other light transmitting material. Optical products can beprepared from high index of refraction materials, including monomerssuch as high index of refraction (meth)acrylate monomers, halogenatedmonomers, and other such high index of refraction monomers as are knownin the art. High refractive index materials such as these and others aredisclosed, for example, in U.S. Pat. Nos. 4,568,445; 4,721,377;4,812,032; 5,424,339; 5,183,917; 6,541,591; 7,491,441; 7,297,810,6,355,754, 7,682,710; 7,642,335; 7,632,904; 7,407,992; 7,375,178;6,117,530; 5,777,433; 6,533,959; 6,541,591; 7,038,745 and U.S. patentapplication Ser. Nos. 11/866,521; 12/165,765; 12/307,555; and Ser. No.11/556,432. High refractive index pressure sensitive adhesives such asthose disclosed in U.S. patent application Ser. No. 12/608,019 may alsobe used as a core layer or layer component.

Low refractive index materials include sol gels, fluoropolymers,fluorinated sol-gels, PMP, and other materials such fluoropolyetherurethanes such as those disclosed in U.S. Pat. No. 7,575,847, and otherlow refractive index material such as those disclosed in U.S. patentapplication Ser. Nos. 11/972,034; 12/559,690; 12/294,694; 10/098,813;11/026,614; and U.S. Pat. Nos. 7,374,812; 7,709,551; 7,625,984;7,164,536; 5,594,830 and 7,419,707.

Materials such a nanoparticles (titanium dioxide, and other oxides forexample), blends, alloys, doping, sol gel, and other techniques may beused to increase or decrease the refractive index of a material.

In another embodiment the refractive index or location of a region oflightguide or lightguide region changes in response to environmentalchanges or controlled changes. These changes can include electricalcurrent, electromagnetic field, magnetic field, temperature, pressure,chemical reaction, movement of particles or materials (such aselectrophoresis or electrowetting), optical irradiation, orientation ofthe object with respect to gravitational field, MEMS devices, MOEMSdevices, and other techniques for changing mechanical, electrical,optical or physical properties such as those known in the of smartmaterials. In one embodiment, the light extraction feature couples moreor less light out of the lightguide in response to an applied voltage orelectromagnetic field. In one embodiment, the light emitting devicecomprises a lightguide wherein properties of the lightguide (such as theposition of the lightguide) which change to couple more or less lightout of a lightguide such as those incorporated in MEMs type displays anddevices as disclosed in U.S. patent application Ser. Nos. 12/511,693;12/606,675; 12/221,606; 12/258,206; 12/483,062; 12/221,193; 11/975,41111/975,398; 10/312,003; 10/699,397 and U.S. Pat. Nos. 7,586,560;7,535,611; 6,680,792; 7,556,917; 7,532,377; and 7,297,471.

Edges of the Lightguide

In one embodiment, the edges of the lightguide or lightguide region arecoated, bonded to or disposed adjacent to a specularly reflectingmaterial, partially diffusely reflecting material, or diffuse reflectingmaterial. In one embodiment, the lightguide edges are coated with aspecularly reflecting ink comprising nano-sized or micron-sizedparticles or flakes which reflect the light substantially specularly. Inanother embodiment, a light reflecting element (such as a specularlyreflecting multi-layer polymer film with high reflectivity) is disposednear the lightguide edge and is disposed to receive light from the edgeand reflect it and direct it back into the lightguide. In anotherembodiment, the lightguide edges are rounded and the percentage of lightdiffracted from the edge is reduced. One method of achieving roundededges is by using a laser to cut the lightguide from a film and achieveedge rounding through control of the processing parameters (speed ofcut, frequency of cut, laser power, etc.). In another embodiment, theedges of the lightguide are tapered, angled serrated, or otherwise cutor formed such that light from a light source propagating within thecoupling lightguide reflects from the edge such that it is directed intoan angle closer to the optical axis of the light source, toward a foldedregion, toward a bent region, toward a lightguide, toward a lightguideregion, or toward the optical axis of the light emitting device. In afurther embodiment, two or more light sources are disposed to eachcouple light into two or more coupling lightguides comprising lightre-directing regions for each of the two or more light sources thatcomprise first and second reflective surfaces which direct a portion oflight from the light source into an angle closer to the optical axis ofthe light source, toward a folded or bent region, toward a lightguideregion, toward a lightguide region, or toward the optical axis of thelight emitting device.

Surfaces of the Lightguide

In one embodiment, at least one surface of the lightguide or lightguideregion is coated, bonded to or disposed adjacent to a specularlyreflecting material, partially diffusely reflecting material, or diffusereflecting material. In one embodiment, at least on lightguide surfaceis coated with a specularly reflecting ink comprising nano-sized ormicron-sized particles or flakes which reflect the light substantiallyspecularly. In another embodiment, a light reflecting element (such as aspecularly reflecting multi-layer polymer film with high reflectivity)is disposed near the lightguide surface opposite the light emittingsurface and is disposed to receive light from the surface and reflect itand direct it back into the lightguide. In another embodiment, the outersurface of at least one lightguide or component coupled to thelightguide comprises a microstructure to reduce the appearance offingerprints. Such microstructures are known in the art of hardcoatingsfor displays and examples are disclosed in U.S. patent application Ser.No. 12/537,930.

Shape of the Lightguide

In one embodiment, at least a portion of the lightguide shape orlightguide surface is at least one selected from the group:substantially planar, curved, cylindrical, a formed shape from asubstantially planar film, spherical, partially spherical, angled,twisted, rounded, have a quadric surface, spheroid, cuboid,parallelepiped, triangular prism, rectangular prism, ellipsoid, ovoid,cone pyramid, tapered triangular prism and other known geometricalsolids or shapes. In one embodiment, the lightguide is a film which hasbeen formed into a shape by thermoforming or other forming technique. Inanother embodiment, the film or region of the film is tapered in atleast one direction. In a further embodiment, a light emitting devicecomprises a plurality of lightguides and a plurality of light sourcesphysically couple or arranged together (such as tiled in a 1×2 array forexample). In another embodiment, the lightguide region of the film issubstantially in the shape of one selected from the group: rectangular,square, circle, doughnut shaped (elliptical with a hole in the innerregion), elliptical, linear strip, tube (with a circular, rectangular,polygonal, or other shaped cross-section).

In one embodiment, a light emitting device comprises a lightguide formedfrom a film into a hollow cylindrical tube comprises coupling lightguidestrips branching from the film on a short edge toward the inner portionof the cylinder. In another embodiment, a light emitting devicecomprises a film lightguide with coupling lightguides cut into the filmso that they remain coupled to the lightguide region and the centralstrip is not optically coupled to the lightguide and provides a spinewith increased stiffness in at least one direction near the centralstrip region or lightguide region near the strip. In a furtherembodiment, a light emitting device comprises lightguides with lightinput couplers arranged such that the light source is disposed in thecentral region of the edge of the lightguide and that the light inputcoupler (or a component thereof) does not extend past the edge andenables the lightguides to be tiled in at least one of a 1×2, 2×2, 2×3,3×3 or larger array. In another embodiment, a light emitting devicecomprises light emitting lightguides wherein the separation between thelightguides in at least one direction along the light emitting surfaceis less than one selected from the group: 10 mm, 5 mm, 3 mm, 2 mm, 1 mm,and 0.5 mm.

In another embodiment, the lightguide comprises single fold or bend nearan edge of the lightguide such that the lightguide folds under or overitself. In this embodiment, light which would ordinarily be lost at theedge of a lightguide may be further extracted from the lightguide afterthe fold or bend to increase the optical efficiency of the lightguide ordevice. In another embodiment, the light extraction features on thelightguide disposed in the optical path of the light within thelightguide after the fold or bend provide light extraction features thatincrease at least one selected from the group: the luminance, luminanceuniformity, color uniformity, optical efficiency, and image or logoclarity or resolution.

Edges Fold Around Back onto the Lightguide

In one embodiment, at least one edge region of one or more selected fromthe group: lightguide, lightguide region, and coupling lightguides foldsor bends back upon itself and is optically coupled to the lightguide,lightguide region or coupling lightguide such that a portion enteringthe edge region is coupled back into the lightguide, lightguide region,or coupling lightguide in a direction away from the edge region. Theedge regions may be adhered using an adhesive such as PSA or otheradhesive, thermally bonded, or otherwise optically coupled back onto thelightguide, lightguide region, or coupling lightguide. In oneembodiment, folding the edge regions of the lightguide redirects lightthat would normally exit the edge of the film back into the lightguide,and the optical efficiency of the system is increased.

In another embodiment, the thickness of the lightguide, lightguideregion, or coupling lightguide is thinner in the region near an edgethan the average thickness of the lightguide in the light emittingregion or lightguide region. In another embodiment, the thickness of thelightguide, lightguide region, or coupling lightguide is less than oneselected from the group: 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%,and 5% of the average thickness of the lightguide in the light emittingregion or lightguide region.

In one embodiment, the thickness of the lightguide, lightguide region,or coupling lightguide is tapered in the region near an edge. In oneembodiment, tapering the thickness in the region near edge permits morelight to couple back into the lightguide when it is optically coupled tothe surface of the lightguide or lightguide region.

In one embodiment, the light emitting device has an optical efficiency,defined as the luminous flux of the light exiting the light emittingdevice in the light emitting region divided by the luminous flux of thelight exiting the light source disposed to direct light into the inputcoupler, greater than one selected from the group: 50%, 60%, 70%, 80%,and 90%.

In another embodiment, the edge region of a lightguide not disposed toreceive light directly from a light source or light input coupler isformed or coupled into a light output coupler comprising couplinglightguides which are folded or bent to create a light output surface.In another embodiment, the light output surface is optically coupled toor disposed proximal to a light input surface of a light input couplerfor the same lightguide or film or a second lightguide or film. In thisembodiment, the light reaching the edge of a lightguide may be coupledinto coupling strips which are folded and bent to direct light back intothe lightguide and recycle the light.

Lightguide Material

In one embodiment, a light emitting device comprises a lightguide orlightguide region formed from at least one light transmitting material.In one embodiment, the lightguide is a film comprising at least one coreregion and at least one cladding region, each comprising at least onelight transmitting material. In one embodiment, the core material issubstantially flexible (such as a rubber or adhesive) and the claddingmaterial supports and provides at least one selected from the group:increased flexural modulus, increased impact strength, increased tearresistance, and increased scratch resistance for the combined element.In another embodiment, the cladding material is substantially flexible(such as a rubber or adhesive) and the core material supports andprovides at least one selected from the group: increased flexuralmodulus, increased impact strength, increased tear resistance, andincreased scratch resistance for the combined element.

The light transmitting material used within an embodiment may be athermoplastic, thermoset, rubber, polymer, high transmission silicone,glass, composite, alloy, blend, silicone, other light transmittingmaterial, or a combination thereof.

In one embodiment, a component or region of the light emitting devicecomprises a light transmitting material selected from the group:cellulose derivatives (e.g., cellulose ethers such as ethylcellulose andcyanoethylcellulose, cellulose esters such as cellulose acetate),acrylic resins, styrenic resins (e.g., polystyrene), polyvinyl-seriesresins [e.g., poly(vinyl ester) such as poly(vinyl acetate), poly(vinylhalide) such as poly(vinyl chloride), polyvinyl alkyl ethers orpolyether-series resins such as poly(vinyl methyl ether), poly(vinylisobutyl ether) and poly(vinyl t-butyl ether)], polycarbonate-seriesresins (e.g., aromatic polycarbonates such as bisphenol A-typepolycarbonate), polyester-series resins (e.g., homopolyesters, forexample, polyalkylene terephthalates such as polyethylene terephthalateand polybutylene terephthalate, polyalkylene naphthalates correspondingto the polyalkylene terephthalates; copolyesters containing an alkyleneterephthalate and/or alkylene naphthalate as a main component;homopolymers of lactones such as polycaprolactone), polyamide-seriesresin (e.g., nylon 6, nylon 66, nylon 610), urethane-series resins(e.g., thermoplastic polyurethane resins), copolymers of monomersforming the above resins [e.g., styrenic copolymers such as methylmethacrylate-styrene copolymer (MS resin), acrylonitrile-styrenecopolymer (AS resin), styrene-(meth)acrylic acid copolymer,styrene-maleic anhydride copolymer and styrene-butadiene copolymer,vinyl acetate-vinyl chloride copolymer, vinyl alkyl ether-maleicanhydride copolymer]. Incidentally, the copolymer may be whichever of arandom copolymer, a block copolymer, or a graft copolymer.

Lightguide Material Comprises Glass

In one embodiment, the coupling lightguides comprise a core materialcomprising a glass material. In one embodiment, the glass material isone selected from the group: fused silica, ultraviolet grade fusedsilica (such as JGS1 by Dayoptics Inc., Suprasil® 1 and 2 by HeraeusQuartz America, LLC., Spectrosil® A and B by Saint-Gobain Quartz PLC,and Corning 7940 by Corning Incorporated, Dynasil® Synthetic FusedSilica 1100 and 4100 by Dynasil Corporation), optical grade fusedquartz, full spectrum fused silica, borosilicate glass, crown glass, andaluminoborosilicate glass.

In another embodiment, the core material comprises a glass which iscoated, or has an organic material applied to at least one selected fromthe group: edge, top surface, and bottom surface. In one embodiment, thecoating on the glass functions to at least one selected from the group:provide a cladding region, increase impact resistance, and provideincreased flexibility. In another embodiment, the coupling lightguidescomprising glass, a polymeric material, or a rubber material are heatedto a temperature above their glass transition temperature or VICATsoftening point before folding in a first direction.

Multilayer Lightguide

In one embodiment, the lightguide comprises at least two layers orcoatings. In another embodiment, the layers or coatings function as atleast one selected from the group: a core layer, a cladding layer, a tielayer (to promote adhesion between two other layers), a layer toincrease flexural strength, a layer to increase the impact strength(such as Izod, Charpy, Gardner, for example), and a carrier layer. In afurther embodiment, at least one layer or coating comprises amicrostructure, surface relief pattern, light extraction features,lenses, or other non-flat surface features which redirect a portion ofincident light from within the lightguide to an angle whereupon itescapes the lightguide in the region near the feature. For example, thecarrier film may be a silicone film with embossed light extractionfeatures disposed to receive a thermoset polycarbonate resin. In anotherembodiment, the carrier film is removed from contact with the corematerial in at least one region. For example, the carrier film may be anembossed FEP film and a thermoset methacrylate based resin is coatedupon the film and cured by heat, light, other radiation, or acombination thereof. In another embodiment, the core material comprisesa methacrylate material and the cladding comprises a silicone material.In another embodiment, a cladding material is coated onto a carrier filmand subsequently, a core layer material, such as a silicone, a PC, or aPMMA based material, is coated or extruded onto the cladding material.In one embodiment, the cladding layer is too thin to support itself in acoating line and therefore a carrier film is used. The coating may havesurface relief properties one the side opposite the carrier film, forexample.

In one embodiment, the lightguide comprises a core material disposedbetween two cladding regions wherein the core region comprises apolymethyl methacrylate, polystyrene, or other amorphous polymer and thelightguide is bent at a first radius of curvature and the core regionand cladding region are not fractured in the bend region, wherein thesame core region comprising the same polymethyl methacrylate without thecladding regions or layers fractures more than 50% of the time when benta the first radius of curvature. In another embodiment, a lightguidecomprises substantially ductile polymer materials disposed on both sidesof a substantially brittle material of a first thickness such as PMMA orpolystyrene without impact modifiers and the polymer fracture toughnessor the ASTM D4812 un-notched Izod impact strength of the lightguide isgreater than a single layer of the brittle material of a firstthickness.

Core Region Comprising a Thermoset Material

In one embodiment, a thermoset material is coated onto a thermoplasticfilm wherein the thermoset material is the core material and thecladding material is the thermoplastic film or material. In anotherembodiment, a first thermoset material is coated onto a film comprisinga second thermoset material wherein the first thermoset material is thecore material and the cladding material is the second thermoset plastic.

In one embodiment, an epoxy resin that has generally been used as amolding material may be used as the epoxy resin (A). Examples includeepoxidation products of novolac resins derived from phenols andaldehydes, such as phenol novolac epoxy resins and ortho-cresol novolacepoxy resins; diglycidyl ethers of bisphenol A, bisphenol F, bisphenolS, alkyl-substituted bisphenol, or the like; glycidylamine epoxy resinsobtained by the reaction of a polyamine such as diaminodiphenylmethaneand isocyanuric acid with epichlorohydrin; linear aliphatic epoxy resinsobtained by oxidation of olefin bonds with a peracid such as peraceticacid; and alicyclic epoxy resins. Any two or more of these resins may beused in combination. Examples of thermoset resins further includebisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxyresins, diglycidyl isocyanurate, and triglycidyl isocyanurate, P(MMA-d8)material, fluorinated resin, deuterated polymer, poly(fluoroalkyl-MA),poly(deuterated fluoroalkyl-MA), trideutero hexafluorobutyl-pentadeuteromethacrylate, and triazine derived epoxy resin.

In another embodiment, the thermosetting resin is a thermosettingsilicone resin. In a further embodiment, the thermosetting siliconeresin composition comprises a condensation reactable substituentgroup-containing silicon compound and an addition reactable substituentgroup-containing silicon compound. In another embodiment, thethermosetting silicone resin composition comprises a dual-end silanoltype silicone oil as the condensation reactable substituentgroup-containing silicon compound; an alkenyl group-containing siliconcompound; an organohydrogensiloxane as the addition reactablesubstituent group-containing silicon compound; a condensation catalyst;and a hydrosilylation catalyst. In one embodiment, the thermosettingresin is a methylphenyl dimethyl copolymer or comprises a silicone basedmaterial such as disclosed in U.S. Pat. No. 7,551,830, the contents ofwhich are incorporated by reference herein. In another embodiment, thethermosetting resin comprises a polydiorganosiloxane having an average,per molecule, of at least two aliphatically unsaturated organic groupsand at least one aromatic group; (B) a branched polyorganosiloxanehaving an average, per molecule, of at least one aliphaticallyunsaturated organic group and at least one aromatic group; (C) apolyorganohydrogensiloxane having an average per molecule of at leasttwo silicon-bonded hydrogen atoms and at least one aromatic group, (D) ahydrosilylation catalyst, and (E) a silylated acetylenic inhibitor. Inanother embodiment, the thermosetting comprises a silicone,polysiloxane, or silsesquioxane material such as disclosed in U.S.patent application Ser. Nos. 12/085,422 and 11/884,612.

In a further embodiment, the thermosetting material comprises: a liquidcrystalline thermoset oligomer containing at least aromatic or alicyclicstructural unit with a kink structure in the backbone and having one ortwo thermally crosslinkable reactive groups introduced at one or bothends of the backbone; either a crosslinking agent having thermallycrosslinkable reactive groups at both ends thereof or an epoxy compoundor both; and an organic solvent. In a further embodiment, thethermosetting composition comprises at least one selected from thegroup: an aluminosiloxane, a silicone oil containing silanol groups atboth ends, an epoxy silicone, and a silicone elastomer. In thisthermosetting composition, it is considered that each of hydroxyl groupsof the aluminosiloxane and/or the silicone oil containing silanol groupsat both ends, and a highly reactive epoxy group of the epoxy siliconeare reacted and cross-linked, at the same time the silicone elastomer iscross-linked by a hydrosilylation reaction therewith. In anotherembodiment, the thermoset is a photopolymerizable composition. Inanother embodiment, the photopolymerizable composition comprises: asilicon-containing resin comprising silicon-bonded hydrogen andaliphatic unsaturation, a first metal-containing catalyst that may beactivated by actinic radiation, and a second metal-containing catalystthat may be activated by heat but not the actinic radiation.

In another embodiment, the thermosetting resin comprises asilsesquioxane derivative or a Q-containing silicone. In anotherembodiment, the thermosetting resin is a resin with substantially hightransmission such as those disclosed in U.S. patent application Ser.Nos. 12/679,749, 12/597,531, 12/489,881, 12/637,359, 12/637,359,12/549,956, 12/759,293, 12/553,227, 11/137,358, 11/391,021, and11/551,323.

In a further embodiment, the lightguide comprises a thermoset resin thatis coated onto an element of the light emitting device (such as acarrier film with a coating, an optical film, the rear polarizer in anLCD, a brightness enhancing film, a thermal transfer element such as athin sheet comprising aluminum, or a white reflector film) andsubsequently cured or thermoset.

Lightguide Material with Adhesive Properties

In another embodiment, the lightguide comprises a material with at leastone selected from the group: chemical adhesion, dispersive adhesion,electrostatic adhesion, diffusive adhesion, and mechanical adhesion toat least one element of the light emitting device (such as a carrierfilm with a coating, an optical film, the rear polarizer in an LCD, abrightness enhancing film, another region of the lightguide, a couplinglightguide, a thermal transfer element such as a thin sheet comprisingaluminum, or a white reflector film). In a further embodiment, at leastone of the core material or cladding material of the lightguide is anadhesive material. In a further embodiment, at least one selected fromthe group: core material, cladding material, and material disposed on acladding material of the lightguide is at least one selected from thegroup: pressure sensitive adhesive, contact adhesive, hot adhesive,drying adhesive, multi-part reactive adhesive, one-part reactiveadhesive, natural adhesive, and synthetic adhesive. In a furtherembodiment, the first core material of a first coupling lightguide isadhered to the second core material of a second coupling lightguide dueto the adhesion properties of the first core material, second corematerial, or a combination thereof. In one embodiment, the core layer isan adhesive and is coated onto at least one selected from the group:cladding layer, removable support layer, protective film, secondadhesive layer, polymer film, metal film, second core layer, low contactarea cover, and planarization layer. In another embodiment, the claddingmaterial of a first coupling lightguide is adhered to the core materialof a second coupling lightguide due to the adhesion properties of thecladding material. In another embodiment, the first cladding material ofa first coupling lightguide is adhered to the second cladding materialof a second coupling lightguide due to the adhesion properties of thefirst cladding material, second cladding material, or a combinationthereof. In another embodiment, the cladding material or core materialhas adhesive properties and has an ASTM D3330 Peel strength greater thanone selected from the group: 929, 17.858, 35.716, 53.574, 71.432, 89.29,107.148, 125.006, 142.864, 160.722, 178.580 kilograms per meter of bondwidth when adhered to an element of the light emitting device, such asfor example without limitation, a cladding layer, a core layer, a lowcontact area cover, a circuit board, or a housing.

In another embodiment, a tie layer, primer, or coating is used topromote adhesion between at least one selected from the group: corematerial and cladding material, lightguide and housing, core materialand element of the light emitting device, cladding material and elementof the light emitting device. In one embodiment, the tie layer orcoating comprises a dimethyl silicone or variant thereof and a solvent.In another embodiment, the tie layer comprises a phenyl based primersuch as those used to bridge phenylsiloxane-based silicones withsubstrate materials. In another embodiment, the tie layer comprises aplatinum-catalyzed, addition-cure silicone primer such as those used tobond plastic film substrates and silicone pressure sensitive adhesives.

In a further embodiment, at least one region of the core material orcladding material has adhesive properties and is optical coupled to asecond region of the core or cladding material such that the ASTM D1003luminous transmittance of visible light through the interface is atleast one selected from the group: 1%, 2%, 3%, and 4% greater than thetransmission through the same two materials at the same region with anair gap disposed between them.

Outermost Surface of the Film or Lightguide

In one embodiment, the outermost surface of the film, lightguide orlightguide region comprises at least one selected from the group:cladding, surface texture to simulate a soft feel or match the surfacetexture of cloth or upholstery, a refractive element to collimate lightfrom the light extraction features (such as microlens array), anadhesive layer, a removable backing material, an anti-reflectioncoating, an anti-glare surface, and a rubber surface.

Light Extraction Method

In one embodiment, at least one of the lightguide, lightguide region, orlight emitting region comprises at least one light extraction feature orregion. In one embodiment, the light extraction region may be a raisedor recessed surface pattern or a volumetric region. Raised and recessedsurface patterns include scattering material, raised lenses, scatteringsurfaces, pits, grooves, surface modulations, microlenses, lenses,diffractive surface features, holographic surface features, wavelengthconversion materials, holes, edges of layers (such as regions where thecladding is removed from covering the core layer), pyramid shapes, prismshapes, and other geometrical shapes with flat surfaces, curvedsurfaces, random surfaces, quasi-random surfaces or a combinationthereof. The volumetric scattering regions within the light extractionregion may comprise dispersed phase domains, voids, absence of othermaterials or regions (gaps, holes), air gaps, boundaries between layersand regions, and other refractive index discontinuities within thevolume of the material different that co-planar layers with parallelinterfacial surfaces. In one embodiment, the light extracting regioncomprises angled or curved surface or volumetric light extractingfeatures that redirect a first redirection percentage of light into anangular range within 5 degrees of the normal to the light emittingsurface of the light emitting device. In another embodiment, the firstredirection percentage is greater than one selected from the group: 5,10, 20, 30, 40, 50, 60, 70, 80, and 90. In one embodiment, the lightextraction features are light redirecting features, light extractingregions or light output coupling features.

In one embodiment, the lightguide or lightguide region comprises lightextraction features in a plurality of regions. In one embodiment, thelightguide or lightguide region comprises light extraction features onor within at least one selected from the group: one outer surface, twoouter surfaces, two outer and opposite surfaces, an outer surface and atleast one region disposed between the two outer surfaces, within twodifferent volumetric regions substantially within two differentvolumetric planes parallel to at least one outer surface or lightemitting surface or plane, and within a plurality of volumetric planes.In another embodiment, a light emitting device comprises a lightemitting region on the lightguide region of a lightguide comprising morethan one region of light extraction features. In another embodiment, oneor more light extraction features are disposed on top of another lightextraction feature. For example, grooved light extraction features couldcomprise light scattering hollow microspheres which may increase theamount of light extracted from the lightguide or which could furtherscatter or redirect the light that is extracted by the grooves. Morethan one type of light extraction feature may be used on the surface,within the volume of a lightguide or lightguide region, or a combinationthereof.

In a further embodiment, the light extraction features are grooves,indentations, curved, or angled features that redirect a portion oflight incident in a first direction to a second direction within thesame plane through total internal reflection. In another embodiment, thelight extraction features redirect a first portion of light incident ata first angle into a second angle greater than the critical angle in afirst output plane and increase the angular full width at half maximumintensity in a second output plane orthogonal to the first. In a furtherembodiment, the light extraction feature is a region comprising agroove, indentation, curved or angled feature and further comprises asubstantially symmetric or isotropic light scattering region of materialsuch as dispersed voids, beads, microspheres, substantially sphericaldomains, or a collection of randomly shaped domains wherein the averagescattering profile is substantially symmetric or isotropic. In a furtherembodiment, the light extraction feature is a region comprising agroove, indentation, curved or angled feature and further comprises asubstantially anisotropic or asymmetric light scattering region ofmaterial such as dispersed elongated voids, stretched beads,asymmetrically shaped ellipsoidal particles, fibers, or a collection ofshaped domains wherein the average scattering is profile issubstantially asymmetric or anisotropic. In one embodiment, theBidirectional Scattering Distribution Function (BSDF) of the lightextraction feature is controlled to create a predetermined light outputprofile of the light emitting device or light input profile to a lightredirecting element.

In one embodiment, at least one light extraction feature is an array,pattern or arrangement of a wavelength conversion material selected fromthe group: a fluorophore, phosphor, a fluorescent dye, an inorganicphosphor, photonic bandgap material, a quantum dot material, afluorescent protein, a fusion protein, a fluorophores attached toprotein to specific functional groups, quantum dot fluorophores, smallmolecule fluorophores, aromatic fluorophores, conjugated fluorophores,and a fluorescent dye scintillators, phosphors such as Cadmium sulfide,rare-earth doped phosphor, and other known wavelength conversionmaterials.

In one embodiment, the light extraction feature is a specularly,diffusive, or a combination thereof reflective material. For example,the light extraction feature may be a substantially specularlyreflecting ink disposed at an angle (such as coated onto a groove) or itmay be a substantially diffusely reflective ink such as an inkcomprising titanium dioxide particles within a methacrylate-based binder(white paint). Alternatively, the light extraction feature may be apartially diffusively reflecting ink such as an ink with small silverparticles (micron or sub-micron, spherical or non-spherical, plate-likeshaped or non-plate-like shaped, or silver (or aluminum) coated ontoflakes) further comprising titanium dioxide particles. In anotherembodiment, the degree of diffusive reflection is controlled to optimizeat least one selected from the group: the angular output of the device,the degree of collimation of the light output, and the percentage oflight extracted from the region.

The pattern or arrangement of light extraction features may vary insize, shape, pitch, location, height, width, depth, shape, orientation,in the x, y, or z directions. Patterns and formulas or equations toassist in the determination of the arrangement to achieve spatialluminance or color uniformity are known in the art of edge-illuminatedbacklights. In one embodiment, a light emitting device comprises afilm-based lightguide comprising light extraction features disposedbeneath lenticules wherein the light extraction features aresubstantially arranged in the form of dashed lines beneath thelenticules such that the light extracted from the line features has alower angular FHWM intensity after redirection from the lenticular lensarray light redirecting element and the length of the dashes varies toassist with the uniformity of light extraction. In another embodiment,the dashed line pattern of the light extraction features varies in the xand y directions (where the z direction is the optical axis of the lightemitting device). Similarly, a two-dimensional microlens array film(close-packed or regular array) or an arrangement of microlenses may beused as a light redirecting element and the light extraction featuresmay comprise a regular, irregular, or other arrangement of circles,ellipsoidal shapes, or other pattern or shape that may vary in size,shape, or position in the x direction, y direction, or a combinationthereof.

Visibility of Light Extraction Features

In one embodiment, at least one light extraction region comprises lightextraction features which have a low visibility to the viewer when theregion is not illuminated by light from within the lightguide (such aswhen the device is in the off-state or the particular lightguide in amulti-lightguide device is not illuminated). In one embodiment, theluminance at a first measurement angle of at least one selected from thegroup: lightguide region, square centimeter measurement area of thelight emitting surface corresponding to light redirected by at least onelight extraction feature, light emitting region, light extractionfeature, and light extracting surface feature or collection of lightextraction features is less than one selected from the group: 0.5 cd/m²,1 cd/m², 5 cd/m², 10 cd/m², 50 cd/m², and 100 cd/m² when exposed todiffuse illuminance from an integrating sphere of one selected from thegroup: 10 lux, 50 lux, 75 lux, 100 lux, 200 lux, 300 lux, 400 lux, 500lux, 750 lux, and 1000 lux when place over a black, light absorbingsurface. Examples of a light absorbing surface include, withoutlimitation, a black velour cloth material, black anodized aluminum,material with a diffuse reflectance (specular component included) lessthan 5%, Light Absorbing Black-Out Material from Edmund Optics Inc., anda window to a light trap box (box with light absorbing black velourlining the walls). In one embodiment, the first measurement angle forthe luminance is one selected from the group: 0 degrees, 5 degrees, 8degrees, 10 degrees, 20 degrees, 40 degrees, 0-10 degrees, 0-20 degrees,0-30 degrees, and 0-40 degrees from the normal to the surface. In oneembodiment, the luminance of the light emitted from a 1 cm² measurementarea of the light emitting surface corresponding to light redirected byat least one light extracting feature is less than 100 cd/m2 whenexposed to a diffuse illuminance of 200 lux from an integrating spherewhen placed over Light Absorbing Black-Out Material from Edmund OpticsInc. In another embodiment, the luminance of the light emitted from a 1cm² measurement area of the light emitting surface corresponding tolight redirected by at least one light extracting feature is less than50 cd/m² when exposed to a diffuse illuminance of 200 lux from anintegrating sphere when placed over Light Absorbing Black-Out Materialfrom Edmund Optics Inc. In another embodiment, the luminance of thelight emitted from a 1 cm² measurement area of the light emittingsurface corresponding to light redirected by at least one or an averageof all light extracting features is less than 25 cd/m² when exposed to adiffuse illuminance of 200 lux from an integrating sphere when placedover Light Absorbing Black-Out Material from Edmund Optics Inc. In oneembodiment, the thin lightguide film permits smaller features to be usedfor light extraction features or light extracting surface features to bespaced further apart due to the thinness of the lightguide. In oneembodiment, the average largest dimensional size of the light extractingsurface features in the plane parallel to the light emitting surfacecorresponding to a light emitting region of the light emitting device isless than one selected from the group: 3 mm, 2 mm, 1 mm, 0.5 mm, 0.25mm, 0.1 mm, 0.080 mm, 0.050 mm, 0.040 mm, 0.025 mm, and 0.010 mm.

In one embodiment, the individual light extracting surface features,regions or pixels are discernible as an individual pixel when the deviceis emitting light in an on state and is not readily discernible when thelight emitting device is in the off state when viewed at a distancegreater than one selected from the group: 10 centimeters, 20centimeters, 30 centimeters, 40 centimeters, 50 centimeters, 100centimeters, and 200 centimeters. In this embodiment, the area mayappear to be emitting light, but the individual pixels or sub-pixelscannot be readily discerned from one another. In another embodiment, theintensity or color of a light emitting region of the light emittingdevice is controlled by spatial or temporal dithering or halftoneprinting. In one embodiment, the average size of the light extractingregions in a square centimeter of a light emitting region on the outersurface of the light emitting device is less than 500 microns and thecolor and/or luminance is varied by increasing or decreasing the numberof light extracting regions within a predetermined area.

In one embodiment, the light emitting device is a sign with a lightemitting surface comprising at least one selected from the group: lightemitting regions, light extracting regions, and light extraction featurewhich is not readily discernible by a person with a visual acuitybetween 0.5 and 1.5 arcminutes at a distance of 20 cm when illuminatedwith 200 lux of diffuse light in front of Light Absorbing Black-OutMaterial from Edmund Optics Inc.

In another embodiment, the fill factor of the light extracting features,defined as the percentage of the surface area comprising lightextracting features in a light emitting region, surface or layer of thelightguide or film, is one selected from the group: less than 80%, lessthan 70%, less than 60%, less than 50%, less than 40%, less than 30%,less than 20%, and less than 10%. The fill factor can be measured withina full light emitting square centimeter surface region or area of thelightguide or film (bounded by regions all directions within the planeof the lightguide which emit light) or it may be the average of thelight emitting areas of the lightguides. The fill factor may be measuredwhen the light emitting device is in the on state or in the off state(not emitting light).

In another embodiment, the light emitting device is a sign with a lightemitting surface comprising light emitting regions wherein when thedevice is not emitting light, the angle subtended by two neighboringlight extracting features that are visible when the device is on, at adistance of 20 cm is less than one selected from the group: 0.001degrees, 0.002 degrees, 0.004 degrees, 0.008 degrees, 0.010 degrees,0.015 degrees, 0.0167 degrees, 0.02 degrees, 0.05 degrees, 0.08 degrees,0.1 degrees, 0.16 degrees, 0.2 degrees, 0.3 degrees, 0.4 degrees, 0.5degrees, 0.6 degrees, 0.7 degrees, 0.8 degrees, 1 degree, 2 degrees, and5 degrees. In another embodiment, the light emitting device is a signwith a light emitting surface comprising light emitting regions whereinwhen the device is not emitting light, the angle subtended by twoneighboring light extracting features (that are which are not easilyvisible when the device is off when illuminated with 200 lux of diffuselight) at a distance of 20 cm is less than one selected from the group:0.3 degrees, 0.4 degrees, 0.5 degrees, 0.6 degrees, 0.7 degrees, 0.8degrees, 1 degree, 2 degrees, and 5 degrees.

In a further embodiment, the light extraction features of the lightemitting device comprise light scattering domains of a material with adifferent refractive index than the surrounding material. In oneembodiment, the light scattering domain has a concentration within thecontinuous region having light scattering domains (such as an inkjetdeposited white ink pixel) less than one selected from the group: 50%,40%, 30%, 20%, 10%, 5%, 3%, 1%, 0.5%, and 0.1% by volume or weight. Theconcentration or thickness of the light scattering domains may vary inthe x, y, or z directions and the pixel or region may be overprinted toincrease the thickness. In another embodiment, the light extractingfeatures have a light absorbing region disposed between the lightextracting feature and at least one output surface of the light emittingdevice. For example, the light extracting features could be titaniumdioxide based white inkjet deposited pixels deposited on a lightguideand the light absorbing ink (such as a black dye or ink comprisingcarbon black particles) is deposited on top of the white ink such that50% of the light scattered from the white pixel is transmitted throughthe light absorbing ink. In this example, the ambient light that wouldhave reflected from the white ink if there were no light absorbing inkis reduced by 75% (twice passing through the 50% absorbing ink) and thevisibility of the dots is reduced while sufficient light from thelightguide is emitted from the light emitting device in the region nearthe white pixel. In another embodiment, a low light transmission lightabsorbing material absorbing at least one selected from the group: 5%,10%, 20%, 30%, 40%, 50%, 60%, and 70% of the light emitted from a firstlight extracting feature is disposed between the light extractingfeature and at least one outer surface of the light emitting device.

Multiple Lightguides

In one embodiment, a light emitting device comprises more than onelightguide to provide at least one selected from the group: colorsequential display, localized dimming backlight, red, green, and bluelightguides, animation effects, multiple messages of different colors,NVIS and daylight mode backlight (one lightguide for NVIS, onelightguide for daylight for example), tiled lightguides or backlights,and large area light emitting devices comprised of smaller lightemitting devices. In another embodiment, a light emitting devicecomprises a plurality of lightguides optically coupled to each other. Inanother embodiment, at least one lightguide or a component thereofcomprises a region with anti-blocking features such that the lightguidesdo not substantially couple light directly into each other due totouching. In some embodiments, the need for a cladding can be reduced oralleviated by using anti-blocking materials to maintain separation (andair gap) over regions of the lightguide surfaces. In another embodiment,the light emitting device comprises a first and second light emittingregion disposed to receive light from a first and second group ofcoupling lightguides, respectively, wherein the bends or folds in thefirst group of coupling lightguides are at angle selected from thegroup: 10 to 30 degrees, 25 degrees to 65 degrees, 70 to 110 degrees,115 degrees to 155 degrees, 160 degrees to 180 degrees, and 5 to 180degrees from the bends or folds in the second group of couplinglightguides.

In another embodiment, a film-based lightguide has two separate lightemitting regions with a first and second group of coupling lightguidesdisposed to couple light into the first light emitting region and secondlight emitting region, respectively, wherein the first and second groupsof coupling lightguides fold or bend to create a single light inputcoupler disposed to couple light from a single source or source packageinto both light emitting regions. In a further embodiment, the twoseparate light emitting regions are separated by a separation distance(SD) greater than one selected from the group: 0.1 millimeters, 0.5millimeters, 1 millimeter, 5 millimeters, 10 millimeters, 1 centimeter,5 centimeters, 10 centimeters, 50 centimeters, 1 meter, 5 meters, 10meters, the width of a coupling lightguide, the width of a fold region,a dimension of the first light emitting region surface area, and adimension of the second light emitting region surface area.

In another embodiment, two film-based lightguides are disposed above oneanother in at least one selected from the group: lightguide region,light output region, light input coupler, light input surface, and lightinput edge such that light from a light source, a package of lightsources, an array of light sources, or an arrangement of light sourcesis directed into more than one film-based lightguide.

In a further embodiment, a plurality of lightguides are disposedsubstantially parallel to each other proximate a first light emittingregion and the lightguides emit light of a first and second color. Thecolors may be the same or different and provide additive color, additiveluminance, white light emitting lightguides, red, green, and blue lightemitting lightguides or other colors or combinations of lightguidesemitting light near the same, adjacent or other corresponding lightemitting regions or light extraction features. In another embodiment, alight emitting device comprises a first lightguide and a secondlightguide wherein a region of the second lightguide is disposed beneathfirst lightguide in a direction parallel to the optical axis of thelight emitting device or parallel to the normal to the light emittingsurface of the device and at least one coupling lightguide from thefirst light lightguide is interleaved between at least two couplinglightguides from the second lightguide. In a further embodiment, thecoupling lightguides from the first lightguide film are interleaved withthe coupling lightguides of the second lightguide region. For example,two film-based lightguides with coupling lightguide strips orientedparallel to each other along one edge may be folded together to form asingle light input surface wherein the light input edges forming thelight input surface alternate between the lightguides. Similarly, threeor more lightguides with light input edges 1, 2, and 3 may be collectedthrough folding into a light input surface with alternating input edgesin a 1-2-3-1-2-3-123 . . . pattern along a light input surface.

In another embodiment, a light emitting device comprises a firstlightguide and a second lightguide wherein a region of the secondlightguide is disposed beneath first lightguide in a direction parallelto the optical axis of the light emitting device or parallel to thenormal to the light emitting surface of the device and a first set ofthe coupling lightguides disposed to couple light into the firstlightguide form a first light input surface and are disposed adjacent asecond set of coupling lightguides disposed to couple light into thesecond lightguide. The first and second set of lightguides may be in thesame light input coupler or different light input coupler disposedadjacent each other and they may be disposed to receive light from thesame light source, a collection of light sources, different lightsources, or different collections of light sources.

Multiple Lightguides to Reduce Bend Loss

In another embodiment, a light emitting device comprises a firstlightguide and a second lightguide wherein a first overlapping region ofthe second lightguide is disposed beneath first lightguide in adirection parallel to the optical axis of the light emitting device orparallel to the normal to the light emitting surface of the device andthe first and second set of coupling lightguides disposed to couplelight into the first and second lightguides, respectively, have a totalbend loss less than that of a set of coupling lightguides opticallycoupled to a lightguide covering the same input dimension of each firstand second coupling lightguide with the same radius of curvature as theaverage of the first and second set of coupling lightguides and a corethickness equal to the total core thicknesses of the first and secondlightguides in the first overlapping region.

In a further embodiment, multiple lightguides are stacked such thatlight output from one lightguide passes through at least one region ofanother lightguide and the radii of curvature for a fixed bend loss (percoupling lightguide or total loss) is less than that of a singlelightguide with the same light emitting area, same radius of curvature,and the thickness of the combined lightguides. For example, for a bendloss of 70%, a first lightguide of a first thickness may be limited to afirst radius of curvature. By using a second and third lightguide witheach at half the thickness of the first lightguide, the radius ofcurvature of each of the second and third lightguides can be less tomaintain only 70% bend loss due to the reduced thickness of eachlightguide. In one embodiment, multiple thin lightguides, each with aradius of curvature less than a thicker lightguide with the same bendloss, reduce the volume and form factor of the light emitting device.The light input surfaces of the coupling lightguides from the differentlightguides may be disposed adjacent each other in a first direction, ondifferent sides of the light emitting device, within the same lightinput coupler, within different light input couplers, underneath eachother, alongside each other, or disposed to receive light from the sameor different light sources.

Multiple Lightguides Connected by Coupling Lightguides

In one embodiment, two or more lightguides are optically coupledtogether by a plurality of coupling lightguides. In one embodiment afilm comprises a first continuous lightguide region and strip-likesections cut in a region disposed between the first continuouslightguide region and a second continuous lightguide region. In oneembodiment, the strips are cut and the first and second continuouslightguide regions are translated relative to each other such that thestrips (coupling lightguides in this embodiment) are folding andoverlapping. The resulting first and second lightguide regions may beseparate regions such as a keypad illuminator and an LCD backlight for acellphone which are connected by the coupling lightguides. The first andsecond lightguide regions may also both intersect a light normal to thefilm surface in one or more regions such that the first and secondlightguide regions at least partially overlap. The first and secondlightguide regions may have at least one light input coupler. Bycoupling the first and second lightguide regions together through theuse of coupling lightguides, the light from an input coupler coupledinto the first lightguide region is not lost, coupled out of, orabsorbed when it reaches the end of the first lightguide region and mayfurther propagate to the second lightguide region. This can allow morelight extraction regions for a specific region since the lightguidesoverlap in a region. In one embodiment, at least one region disposed toreceive light between the first and second lightguide regions maycomprise a light absorbing filter such that the light reaching thesecond lightguide region comprises a different wavelength spectralprofile and a second color can be extracted from the second lightguideregion different to the first color extracted from the first lightguideextracting region. More than two lightguide regions illuminated by afirst input coupler with one, two, or more than two light emittingcolors may be used and separate lightguides (or lightguide regions) withseparate light input couplers may be disposed behind, between, or aboveone or more of the lightguide regions illuminated by the first inputcoupler. For example, a first light input coupler directs white lightfrom an LED into the first lightguide region wherein the lightextracting regions extract light creating a first white image, and thelight which is not extracted passes into coupling lightguides on theopposite end which have a striped region optically coupled to thelightguide (such as a red colored ink stripe) which substantiallyabsorbs the non-red portions of the spectrum. This light furtherpropagates into the second lightguide region where a portion of thelight is extracted out of the lightguide as red light in a red image.Similarly, other colors including subtractive colors may be used tocreate multiple-colors of light emitting from multiple lightguideregions and the light extracting region may overlap to create additivecolor mixing. Two or more lightguides or lightguide regions may overlapwherein the optical axes of the light propagating within the lightguideare at approximately 90 degrees to each other.

Lightguide Folding Around Components

In one embodiment, at least one selected from the group: lightguide,lightguide region, light mixing region, plurality of lightguides,coupling lightguides, and light input coupler bends or folds such thatother components of the light emitting device are hidden from view,located behind another component or the light emitting region, or arepartially or fully enclosed. These components around which they may bendor fold include components of the light emitting device such as lightsource, electronics, driver, circuit board, thermal transfer element,spatial light modulator, display, housing, holder, or other componentsare disposed behind the folded or bent lightguide or other region orcomponent. In one embodiment, a frontlight for a reflective displaycomprises a lightguide, coupling lightguides and a light source whereinone or more regions of the lightguide are folded and the light source isdisposed substantially behind the display.

Curled Edge of Lightguide to Recycle Light

In one embodiment, a lightguide edge region is curled back upon itselfand optically coupled to a region of the lightguide such that lightpropagating toward the edge will follow the curl and propagate back intothe lightguide. In one embodiment, the cladding area is removed from thelightguide from both surfaces which are to be optically coupled orbonded together. More than one edge may be curled or bent back uponitself to recycle light back into the lightguide.

Registration Holes and Cavities

one embodiment, at least one selected from the group: lightguide,lightguide region, light mixing region, light input coupler, housing,holding device and plurality of coupling lightguides comprises at leastone opening or aperture suitable for registration with another componentof the device that contains at least one pin or object which may passthrough the at least one opening or aperture. In another embodiment, oneor more of the light turning optical element, coupling lightguides,light redirecting optical element, light coupling optical element,relative position maintaining optical element, circuit board, flexibleconnector, film-based touchscreen, film-based lightguide, and displayfilm substrate comprises a registration opening, aperture, hole, orcavity.

Alignment Guide

In another embodiment, the light turning optical element has analignment guide physically coupled to the light turning optical elementsuch that the guide directs the coupling lightguide input surfaces toalign in at least one of the following directions: a directionperpendicular to the film surface of the coupling lightguides, adirection parallel to the coupling lightguide film surfaces, a directionparallel to the optical axis of the light source, and a directionorthogonal to the optical axis of the light source. In one embodiment,the alignment guide is physically coupled to one or more the following:the light turning optical element, coupling lightguides, lightredirecting optical element, light coupling optical element, relativeposition maintaining optical element, circuit board, light source, lightsource housing, optical element holder or housing, input couplerhousing, alignment mechanism, heat sink for the light source, flexibleconnector, film-based touchscreen, film-based lightguide, and displayfilm substrate. In one embodiment, the alignment guide comprises analignment arm such as a metal or plastic bar or rod with a flexuralmodulus of one of the following: 2 times, 3 times, 4 times, and 5 timesthat of the stacked array of coupling lightguides that it is disposed toguide a stack of coupling lightguides (or an optical element) in apredetermined direction. The alignment guide may have one or more curvedregions to assist in the guiding function without scratching or damagingthe coupling lightguide through sharp edges. In another embodiment, thealignment guide is a cantilever spring that can apply a force againstone or more coupling lightguides to maintain the position of thecoupling lightguide temporarily or permanently. In another embodiment,the alignment guide maintains the relative position of the couplinglightguide near the light input surface while an additional, permanentrelative position method is employed (such as mechanically clamping,adhering using adhesives, epoxy or optical adhesive, forming a housingaround the coupling lightguides, or inserting the coupling into ahousing) which substantially maintains the relative position of thecoupling lightguides to the light source or light input coupler. Inanother embodiment, a cladding layer (such as a low refractive indexadhesive) is disposed on one or more of the following: the top surface,bottom surface, lateral edges, and light input surface of an array ofcoupling lightguides such that when the alignment guide is thermallycoupled to the array of coupling lightguides, less light is absorbed bythe alignment guide.

Alignment Cavity within the Alignment Guide

In one embodiment, the alignment guide comprises a cavity within amechanical coupler in which a stacked array of coupling lightguides maybe disposed to align their light input edges to receive light from alight source. In one embodiment, the alignment guide comprises a thermaltransfer element with an extended arm or rod to align the couplinglightguides in one dimension, apply force vertical force to the couplinglightguides to assist holding them at the correct lateral position and acavity into which the input surface of the coupling lightguides may beplaced such that they are aligned to receive light from the lightsource. In another embodiment, the alignment guide comprises a thermaltransfer element with an extended arm (functioning as a cantileverspring to apply force) and a cavity with a cross sectional vertical andwidth dimension at least as large as the vertical and width dimensions,respectively, of the cross-section of the stacked array of couplinglightguides near their light input surfaces.

Thermally Conductive Alignment Guide

In another embodiment, the alignment guide is thermally and physicallycoupled to the heat sink for the light source. For example, thealignment guide may comprise an aluminum heat sink disposed around andthermally coupled to the light source with an alignment cavity openingdisposed to receive the coupling lightguide such that they are heldwithin the cavity. In this embodiment, the aluminum heat sink serves analignment function and also reduces the heat load from the light source.In another embodiment, the alignment guide comprises an alignment cavityin a thermally conducting material (such as a metal, aluminum, copper,thermally conductive polymer, or a compound comprising thermallyconductive materials) thermally coupled to the coupling lightguides suchthat the alignment guide removes heat from the coupling lightguidesreceived from the light source. When using high power LEDs, for example,the heat from the light source could potentially damage or causeproblems with the coupling lightguides (softening, thermal or opticaldegradation, etc.). By removing the heat from the coupling lightguides,this effect is reduced or eliminated. In one embodiment, the alignmentguide is thermally coupled to one or more coupling lightguides byphysical contact or through the use of an intermediate thermallyconductive material such as a thermally conductive adhesive or grease.

Other Components

In one embodiment, the light emitting device comprises at least oneselected from the group: power supply, batteries (which may be alignedfor a low profile or low volume device), thermal transfer element (suchas a heat sink, heat pipe, or stamped sheet metal heat sink), frame,housing, heat sink extruded and aligned such that it extends parallel toat least one side of the lightguide, multiple folding or holding modulesalong a thermal transfer element or heat sink, thermal transfer elementexposed to thermally couple heat to a surface external to the lightemitting device, and solar cell capable of providing power,communication electronics (such as needed to control light sources,color output, input information, remote communication, Wi-Fi control,Bluetooth control, wireless internet control, etc.), a magnet fortemporarily affixing the light emitting device to a ferrous or suitablemetallic surface, motion sensor, proximity sensor, forward and backwardsoriented motion sensors, optical feedback sensor (including photodiodesor LEDs employed in reverse as detectors), controlling mechanisms suchas switches, dials, keypads (for functions such as on/off, brightness,color, color temp, presets (for color, brightness, color temp, etc.),wireless control), externally triggered switches (door closing switchfor example), synchronized switches, and light blocking elements toblock external light from reaching the lightguide or lightguide regionor to block light emitted from a region of the light emitting devicefrom being seen by a viewer.

In one embodiment, a light emitting device comprises a first set oflight sources comprising a first and second light source disposed tocouple light into a first and second light input coupler, respectively,and further comprising a second set of light sources comprising a thirdand fourth light source disposed to couple light into a first and secondlight input coupler, respectively, wherein the first set of lightsources are thermally coupled to each other and the second set of lightsources are thermally coupled to each other by means of one selectedfrom the group metal core printed circuit board, aluminum component,copper component, metal alloy component, thermal transfer element, orother thermally conducting element. In a further embodiment, the firstand second set of light sources are substantially thermally isolated byseparating the light sources (or substrates for the light sources suchas a PCB) in the region proximate the light sources by an air gap orsubstantially thermally insulating material such as polymersubstantially free of metallic, ceramic, or thermally conductingcomponents. In another embodiment, the first and third light sources aredisposed closer to each other than the first and second light sourcesand more heat from the first light source reaches the second lightsource than reaches the third light source when only the first lightsource is emitting light. More than two light sources disposed to couplelight into more than two coupling lightguides may be thermally coupledtogether by a thermal transfer element and may be separated from asecond set of more than two light sources by an air gap or thermallyinsulating material.

In another embodiment, a light emitting device comprises a filmlightguide that emits light and also detects light changes within thelightguide and provides touch screen functionality. In one embodiment, afilm lightguide comprises coupling lightguides disposed to receive lightfrom a light source and direct the light into a lightguide to provide abacklight or frontlight and at least one coupling lightguide disposed todetect changes in light intensity (such as lower light levels due tolight being frustrated and absorbed by coupling light into a finger intouched location). More than one light intensity detecting lightguidemay be used. Other configurations for optical lightguide based touchscreens are known in the art and may be used in conjunction withembodiments.

In another embodiment a touchscreen comprises at least two filmlightguides. In another embodiment, a touchscreen device comprises alight input coupler used in reverse to couple light from a filmlightguide into a detector. In another embodiment, the light emittingdevice or touch screen is sensitive to pressure in that when a firstfilm or first lightguide is pressed or pressure is applied, the firstfilm is moved into sufficient optical contact with a second film orsecond lightguide wherein at least one of light from the firstlightguide or first lightguide is coupled into is coupled into thesecond film or second lightguide, light from the second film or secondlightguide is coupled into the first film or first lightguide, or lightcouples from each lightguide or film into the other.

Thermal Transfer Element Coupled to Coupling Lightguide

In another embodiment, a thermal transfer element is thermally coupledto a cladding region, lightguide region, lightguide, couplinglightguide, stack or arrangement of coupling lightguides, combination offolded regions in a coupling lightguide, input coupler, window orhousing component of the light input coupler, or housing. In anotherembodiment, the thermal transfer element is thermally coupled to thecoupling lightguides or folded regions of a coupling lightguide to drawheat away from the polymer based lightguide film in that region suchthat a high-power LED or other light source emitting heat toward thelightguides may be used with reduced thermal damage to the polymer. Inanother embodiment, a thermal transfer element is physically andthermally coupled to the cladding region of the light input couplers orfolded regions of a coupling lightguide. The thermal transfer elementmay also serve to absorb light in one more cladding regions by using athermal transfer element that is black or absorbs a significant amountof light (such as having a diffuse reflectance spectral componentincluded less than 50%). In another embodiment, the top surface of theupper coupling lightguide and the bottom surface of the bottom couplinglightguide comprise cladding regions in the regions of the couplinglightguides or folded regions of the coupling lightguide near the lightinput edges. By removing (or not applying or disposing) the claddingbetween the coupling lightguides or folded regions, more light can becoupled into the coupling lightguides or folded regions from the lightsource. Outer cladding layers or regions may be disposed on the outersurfaces to prevent light absorption from contact with other elements orthe housing, or it may be employed on the top or bottom surface, forexample, to physically and thermally couple the cladding region to athermal transfer element to couple the heat out without absorbing lightfrom the core region (and possibly absorbing light within the coreregion).

In one embodiment, a light emitting device comprises a thermal transferelement disposed to receive heat from at least one light source whereinthe thermal transfer element has at least one selected from the group:total thickness, average total thickness, and average thickness, all inthe direction perpendicular to the light emitting device light emittingsurface less than one selected from the group: 10 millimeters, 5millimeters, 4 millimeters, 3 millimeters, 2 millimeters, 1 millimeter,and 0.5 millimeters. In one embodiment, the thermal transfer elementcomprises a sheet or plate of metal disposed on the opposite side of thelightguide as the light emitting surface of the light emitting device.In a further embodiment, a low thermal conductivity component isdisposed between the thermal transfer element and the lightguide. Inanother embodiment, the low thermal conductivity component has a thermalconductivity, k, less than one selected from the group: 0.6, 0.5, 0.4,0.3, 0.2, 0.1 and 0.05 W·m−1·K−1 at a temperature of 296 degrees Kelvin.In a further embodiment, the low thermal conductivity component is awhite reflective polyester based film (or PTFE based film). In a furtherembodiment, a light emitting device comprises a low thermal conductivitycomponent physically coupled to the thermal transfer element and thelight emitting device further comprises at least one selected from thegroup: low refractive index material, cladding region, and a region withan air gap disposed between the low thermal conductivity component andthe lightguide.

In a further embodiment, the thermal transfer element is an elongatedcomponent with a dimension in first direction at least twice as long asthe dimension in either mutually orthogonal direction orthogonal to thefirst direction wherein a portion of the thermal transfer element isdisposed within the bend region of at least one light input coupler. Inanother embodiment, a light emitting device comprises a light inputcoupler wherein a portion of the smallest rectangular cuboid comprisingall of the coupling lightguides within the light input coupler comprisesa thermal transfer element. In another embodiment, a light emittingdevice comprises a light input coupler wherein a portion of the smallestrectangular cuboid comprising all of the coupling lightguides within thelight input coupler comprises an elongated thermal transfer elementselected from the group: pipe from a heat pipe, elongated heat sink,metal thermal transfer element with fins, rod inside the thermaltransfer element, and metal frame.

In another embodiment, the thermal transfer element comprises at leastone metal frame component or elongated metal component that provides atleast one selected from the group: increased rigidity, frame support forsuspension or mounting, protection from accidental contact, and framesupport for a flat or pre-defined non-planar surface. In a furtherembodiment, the thermal transfer element comprises at least two regionsor surfaces oriented at an angle with respect to each other or anopening through the volume that form at least a portion of a channelthrough which air may flow through. In one embodiment, the lightemitting device comprises a plurality of air channels formed by at leastone surface of the thermal element through which air flows and convectsheat away by active or passive air convection from the source generatingthe heat (such as a light source or a processor). In one embodiment, thelight emitting device comprises a plurality of air channels alongvertically oriented sides of the device through which air flows andconvects heat through (naturally or forced air). In another embodiment,the thermal transfer element has a thermal conductivity greater than oneselected from group of 0.5, 0.7, 1, 2, 5, 10, 50, 100, 200, 300, 400,800, and 1000 W·m−1·K−1 at a temperature of 296 degrees Kelvin.

Other Optical Films

In another embodiment, the light emitting device further comprises alight redirecting optical film, element, or region that redirects lightincident at a first range of angles, wavelength range, and polarizationrange into a second range of angles different than the first.

Light Redirecting Optical Element

In one embodiment, the light redirecting optical element is disposedbetween at least one region of the light emitting region and the outersurface of the light emitting device (which may be a surface of thelight redirecting optical element). In a further embodiment, the lightredirecting optical element is shaped or configured to substantiallyconform to the shape of the light emitting region of the light emittingdevice. For example, a light emitting sign may comprise a lightguidefilm that is substantially transparent surrounding the light emittingregion that is in the shape of indicia; wherein the lightguide filmcomprises light extraction features in the region of the indicia; and alight redirecting optical element (such as a film with substantiallyhemispherical light collimating surface features) cut in the shape ofthe light emitting region is disposed between the light emitting regionof the lightguide film and the light emitting surface of the lightemitting device. In another embodiment, a light emitting sign comprisesa film-based lightguide and a light redirecting optical elementcomprising a lens array formed from lenticules or microlenses (such assubstantially hemispherical lenses used in integral images or 3Dintegral displays or photographs) disposed to receive light from thelightguide wherein the lens array separates light from the lightguideinto two or more angularly separated images such that the sign displaysstereoscopic images or indicia. The shape of the lens array film orcomponent in the plane parallel to the lightguide film may besubstantially conformal to the shape of the light emitting region or oneor more sub-regions of the light emitting regions such that sign emitsangularly separated information in the entire light emitting region orone or more sub-regions of the light emitting region. For example, thesign may have a first two-dimensional text region and a second regionwith a stereoscopic image.

Light Reflecting Film

In another embodiment, a light emitting device comprises a lightguidedisposed between a light reflecting film and the light emitting surfaceof the light emitting device. In one embodiment, the light reflectingfilm is a light reflecting optical element. For example, a whitereflective polyester film of at least the same size and shape of thelight emitting region may be disposed on the opposite side of thelightguide as the light emitting surface of the light emitting device orthe light reflecting region may conform to the size and shape of one orall of the light emitting regions, or the light reflecting region may beof a size or shape occupying a smaller area than the light emittingregion. A light reflecting film or component substantially the sameshape as the light emitting region or region comprising light extractingfeatures may maintain the transparency of the light emitting device inthe regions surrounding or between the light emitting regions or regionscomprising light extracting features while increasing the averageluminance in the region on the light emitting surface of the lightemitting device by at least one selected from the group: 20%, 30%, 40%,50%, 60%, 70%, 80%, 90%, 100%, and 110% by reflecting a portion of thelight received toward the light emitting surface.

In one embodiment, the light redirecting optical film, element or regioncomprises at least one surface or volumetric feature selected from thegroup: refractive, prismatic, totally internally reflective, specularreflective element or coating, diffusely reflective element or coating,reflective diffractive optical element, transmissive diffractive opticalelement, reflective holographic optical element, transmissiveholographic optical element, reflective light scattering, transmissivelight scattering, light diffusing, multi-layer anti-reflection coating,moth-eye or substantially conical surface structure type anti-reflectioncoating, Giant Birefringent Optic multilayer reflection, specularlyreflective polarizer, diffusely reflective polarizer, cholestericpolarizer, guided mode resonance reflective polarizer, absorptivepolarizer, transmissive anisotropic scattering (surface or volume),reflective anisotropic scattering (surface or volume), substantiallysymmetric or isotropic scattering, birefringent, optical retardation,wavelength converting, collimating, light redirecting, spatialfiltering, angular dependent scattering, electro-optical (PDLC, liquidcrystal, etc.), electrowetting, electrophoretic, wavelength rangeabsorptive filter, wavelength range reflective filter, structurednano-feature surface, light management components, prismatic structuredsurface components, and hybrids of two or more of the aforementionedfilms or components.

Some examples of light redirecting optical films with prismaticstructured surfaces may include, but are not limited to, Vikuiti™Brightness Enhancement Film (BEF I, BEF II, BEF III, BEF III 90/50 5T,BEF III 90/50 M, BEF III 90/50 M2, BEF III 90/50 7T, BEF III 90/50 10T,BEF III 90/50 AS), Vikuiti™ Transparent Right Angle Film (TRAF),Vikuiti™ Optical Lighting Film (OLF or SOLF), IDF II, TRAF II, or 3M™Diamond Grade™ Sheeting, all of which are available from 3M Company, St.Paul, Minn. Other examples of light management component constructionsmay include the rounded peak/valley films described in U.S. Pat. Nos.5,394,255 and 5,552,907 (both to Yokota et al.), Reverse Prism Film fromMitsubishi Rayon Co., Ltd or other totally internally reflection basedprismatic film such as disclosed in U.S. Pat. Nos. 6,746,130, 6,151,169,5,126,882, and 6,545,827, lenticular lens array film, microlens arrayfilm, diffuser film, microstructure BEF, nanostructure BEF, Rowluxmicrolens film from Rowland Technologies, films with arrangements oflight concentrators such as disclosed in U.S. Pat. No. 7,160,017, andhybrids of one or more of the aforementioned films.

In another embodiment, the light emitting device further comprises anangularly selected light absorbing film, element or region. Angularlyselective light absorbing films may substantially transmit light withina first incident angular range and substantially absorb light within asecond incident angular range. These films can reduce glare light,absorb undesired light at specific angles (such as desired in militaryapplications where stray or unwanted light can illuminate parts of thecockpit or the windshield causing stray reflections. Louver films, suchas those manufactured by skiving a multi-layered material at a firstangle are known in the display industry and include louver films such as3M™ Privacy Film by 3M Company and other angular absorbing orredirecting films such as those disclosed in U.S. Pat. Nos. 7,467,873;3,524,789; 4,788,094; and 5,254,388.

Angular Broadening Element

In a further embodiment, a light emitting device comprises a lightredirecting element disposed to collimate or reduce the angular FWHM ofthe light from the lightguide, a spatial light modulator, and an angularbroadening element such as a diffuser or light redirecting elementdisposed on the viewing side of the spatial light modulator to increasethe angular FWHM of the light exiting the spatial light modulator. Forexample, light may be collimated to pass through or onto pixels orsub-pixels of a spatial light modulator and the light may then angularlybroadened (increase the angular FWHM) to increase the angle of view ofthe device. In a further embodiment, the angular broadening element isdisposed within or on a component of the spatial light modulator. Forexample, a diffuser may be disposed between the outer glass and thepolarizer in a liquid crystal display to broaden the collimated orpartially collimated light after it has been spatially modulated by theliquid crystal layer. In a further embodiment, the light emitting devicemay further comprise a light absorbing film, circular polarizer,microlens type projection screen, or other rear projection type screento absorb a first portion of the ambient light incident on the lightemitting surface to improve the contrast.

Light Absorbing Region or Layer

In one embodiment, at least one selected from the group: cladding,adhesive, layer disposed between the lightguide or lightguide region andthe outer light emitting surface of the light emitting device, patternedregion, printed region, and extruded region on one or more surfaces orwithin the volume of the film comprises a light absorbing material whichabsorbs a first portion of light in a first predetermined wavelengthrange. In one embodiment, the first predetermined wavelength rangeincludes light from 300 nm to 400 nm and the region absorbs UV lightthat could degrade or yellow the lightguide region, layer or otherregion or layer. In one embodiment, the cladding region is disposedbetween the light absorbing region and the lightguide such that thelight propagating through the lightguide and the evanescent portion ofthe light propagating within the lightguide is not absorbed due to theabsorbing region since it does not pass through the absorbing regionunless it is extracted from the lightguide. In another embodiment, thelight absorbing region or layer is an arrangement of light absorbing,light fluorescing, or light reflecting and absorbing regions whichselectively absorb light in a predetermine pattern to provide a lightemitting device with spatially varying luminance or color (such as in adye-sublimated or inject printed overlay which is laminated or printedonto a layer of the film to provide a colored image, graphic, logo orindicia). In another embodiment, the light absorbing region is disposedin close proximity to the light extracting region such that the lightemitted from the light emitting device due to the particular lightextraction feature has a predetermined color or luminous intensity. Forexample, inks comprising titanium dioxide and light absorbing dyes canbe disposed on the lightguide regions such that a portion of the lightreaching the surface of the lightguide in that region passes through thedye and is extracted due to the light extraction feature or the light isextracted by the light extraction feature and passes through the dye.

In one embodiment, a light emitting device comprises a five-layerlightguide region with a UV light absorbing material disposed in theouter layers which are both optically coupled to cladding layers whichare both optically coupled to the inner lightguide layer. In oneembodiment, a 5-layer film comprises a polycarbonate material in thecentral lightguide layer with low refractive index cladding layers of athickness between 1 micron and 150 microns optically coupled to thelightguide layer and a UV light absorbing material in the outer layersof the film.

In another embodiment, a light absorbing material is disposed on oneside of the light emitting device such that the light emitted from thedevice is contrasted spatially against a darker background. In oneembodiment, a black PET layer or region is disposed in proximity to oneside or region of the light emitting device. In another embodiment,white reflecting regions are disposed in proximity to the lightextracting region such that the light escaping the lightguide in thedirection of the white reflecting region is reflected back toward thelightguide. In one embodiment, a lightguide comprises a lightguideregion and a cladding region and a light absorbing layer is disposed(laminated, coated, co-extruded, etc.) on the cladding region. In oneembodiment, light from a laser cuts (or ablates) regions in the lightabsorbing layer and creates light extracting regions in the claddingregion and/or lightguide region. A white reflecting film such as a whitePET film with voids is disposed next to the light absorbing region. Thewhite film may be laminated or spaced by an air gap, adhesive or othermaterial. In this example, a portion of the light extracted in the lightextracting regions formed by the laser is directed toward the white filmand reflected back through the lightguide where a portion of this lightescapes the lightguide on the opposite side and increases the luminanceof the region. This example illustrates where registration of the whitereflecting region, black reflection region, and light extracting regionsare not necessary since the laser created holes in the black film andcreated the light extracting features at the same time. This examplealso illustrates the ability for the light emitting device to display animage, logo, or indicia in the off state where light is not emitted fromthe light source since the white reflective regions reflect ambientlight. This is useful, for example, in a sign application where powercan be saved during the daytime since ambient light can be used toilluminate the sign. The light absorbing region or layer may also be acolored other than black such as red, green, blue, yellow, cyan,magenta, etc.

In another embodiment, the light absorbing region or layer is a portionof another element of the light emitting device. In one embodiment, thelight absorbing region is a portion of the black housing comprising atleast a portion of the input coupler that is optically coupled to thecladding region using an adhesive.

In another embodiment, the cladding, outer surface or portion of thelightguide of a light emitting device comprises a light absorbing regionsuch as a black stripe region that absorbs more than one selected fromthe group: 50%, 60%, 70%, 80% and 90% of the visible light propagatingwithin the cladding region. In another embodiment, the lightguide isless than 200 microns in thickness and a light absorbing regionoptically coupled to the cladding absorbs more than 70% of the lightpropagating within the cladding which passes through the lightguidewherein the width of the light absorbing region in the direction of thelight propagating within the lightguide is less than one selected fromthe group: 10 millimeters, 5 millimeters, 3 millimeters, 2 millimeters,and 1 millimeter. In another embodiment, the light absorbing region hasa width in the direction of propagation of light within the lightguidebetween one selected from the group: 0.5-3 millimeters, 0.5-6millimeters, 0.5-12 millimeters, and 0.05-10 centimeters.

In one embodiment, the light absorbing region is at least one selectedfrom the group: a black material patterned into a line, a materialpatterned into a shape or collection of shapes, a material patterned onone or both sides of the film, cladding, or layer optically coupled tothe cladding, a material patterned on one or more lightguide couplers, amaterial patterned in the light mixing region, a material patterned inthe lightguide, and a material patterned in the lightguide region. Inanother embodiment, the light absorbing region is patterned during thecutting step for the film, coupling lightguides, or cutting step ofother regions, layers or elements. In another embodiment, the lightabsorbing region covers at least one percentage of surface area of thecoupling lightguides selected from the group: 1%, 2%, 5%, 10%, 20%, and40%.

Adhesion Properties of the Lightguide, Film, Cladding or Other Layer

In one embodiment, at least one selected from the group: lightguide,light transmitting film, cladding, and layer disposed in contact with alayer of the film has adhesive properties. In one embodiment, thecladding is a “low tack” adhesive that allows the film to be removedfrom a window or substantially planar surface while “wetting out” theinterface. By “wetting out” the interface as used herein, the twosurfaces are optically coupled such that the Fresnel reflection from theinterfaces at the surface is less than 2%. The adhesive layer or regionmay comprise a polyacrylate adhesive, animal glue or adhesive,carbohydrate polymer as an adhesive, natural rubber based adhesive,polysulfide adhesive, tannin based adhesive, lignin based adhesive,furan based adhesive, urea formaldehyde adhesive, melamine formaldehydeadhesive, isocyanate wood binder, polyurethane adhesive, polyvinyl andethylene vinyl acetate, hot melt adhesive, reactive acrylic adhesive,anaerobic adhesive, or epoxy resin adhesive.

In one embodiment, the adhesive layer or region has an ASTM D 903(modified for 72-hour dwell time) peel strength to standard window glassless than one selected from the group 77 N/100 mm, 55 N/100 mm, 44 N/100mm, 33 N/100 mm, 22 N/100 mm, and 11 N/100 mm. In another embodiment,the adhesive, when adhered to glass, will support the weight of thelight emitting device.

Removable Protective Layer

In one embodiment, the light emitting device comprises a removableprotective layer. In another embodiment, a light transmitting film isdisposed on the outer surface of the light emitting device and the ASTMD 903 (modified for 72-hour dwell time) peel strength to the lightguideis less than one selected from the group 77 N/100 mm, 55 N/100 mm, 44N/100 mm, 33 N/100 mm, 22 N/100 mm, and 11 N/100 mm. In anotherembodiment, when the outer surface of the light emitting device becomesscratched, damaged, or reduces the optical performance of the lightemitting device, the outer layer of the film may be removed. In afurther embodiment, a tag or extended region of the protective layerallows the individual layer to be removed while maintaining theintegrity or position of the lightguide beneath which may have one ormore additional protective layers disposed thereupon. In one embodiment,a thin film-based lightguide disposed as a frontlight for a reflectivedisplay comprises removable protective layers. The protective layers maybe thin or thick and may comprise materials such as those used asdisplay screen protectors, anti-reflection coatings, anti-glare coatingsor surfaces, hardcoatings, circular polarizers, or surface structuresthat reduce the visibility of fingerprints such as those disclosed inU.S. patent application Ser. No. 12/537,930.

Lightguide Comprising Circuitry or Electrical Components

In one embodiment, at least one electrical component is physicallydisposed on the lightguide or a layer physically coupled to thelightguide. By incorporating electrical components on the lightguidefilm, a separate substrate for one or more electrical components is notneeded (thus lower volumes and component costs) and flexibleroll-to-roll processing can be employed to manufacture or dispose theelectrical component on the lightguide film. In another embodiment, thelightguide comprises at least one electrical component physicallycoupled to a cladding region, a cladding layer, or a layer or regionphysically coupled to the core material or the cladding material. Inanother embodiment, a light emitting device comprises a flexible layercomprising a plurality of electrical components and the layer isphysically coupled to a flexible lightguide film. In one embodiment, alightguide comprises at least one electrical component or component usedwith electrical component disposed thereon, wherein the at least onecomponent is selected from the group: active electrical component,passive electrical component, transistor, thin film transistor, diode,resistor, terminal, connector, socket, cord, lead, switch, keypad,relay, reed switch, thermostat, circuit breaker, limit switch, mercuryswitch, centrifugal switch, resistor, trimmer, potentiometer, heater,resistance wire, thermistor, varistor, fuse, resettable fuse, metaloxide varistor, inrush current limiter, gas discharge tube, circuitbreaker, spark gap, filament lamp, capacitor, variable capacitor,inductor, variable inductor, saturable inductor, transformer, magneticamplifier, ferrite impedance, motor, generator, solenoid, speaker,microphone, RC circuit, LC circuit, crystal, ceramic resonator, ceramicfilter, surface acoustic wave filter, transducer, ultrasonic motor,power source, battery, fuel cell, power supply, photovoltaic device,thermo electric generator, electrical generator, sensor, buzzer, linearvariable differential transformer, rotary encoder, inclinometer, motionsensor, flow meter, strain gauge, accelerometer, thermocouple,thermopile, thermistor, resistance temperature detector, bolometer,thermal cutoff, magnetometer, hygrometer, photo resistor, solid statecomponent, standard diode, rectifier, bridge rectifier, Schottky diode,hot carrier diode, zener diode, transient voltage suppression diode,varactor, tuning diode, varicap, variable capacitance diode, lightemitting diode, laser, photodiode, solar cell, photovoltaic cell,photovoltaic array, avalanche photodiode, diode for alternating current,DIAC, trigger diode, SIDAC, current source diode, Peltier cooler,transistor, bipolar transistor, bipolar junction transistor,phototransistor, Darlington transistor (NPN or PNP), Sziklai pair, fieldeffect transistor, junction field effect transistor, metal oxidesemiconductor FET, metal semiconductor FET, high electron mobilitytransistor, thyristor, unijunction transistor, programmable unijunctiontransistor, silicon controlled rectifier, static inductiontransistor/thyristor, triode for alternating current, compositetransistor, insulated gate bipolar transistor, hybrid circuits,optoelectronic circuit, opto-isolator, opto-coupler, photo-coupler,photodiode, BJT, JFET, SCR, TRIAC, open collector IC, CMOS IC, solidstate relay, opto switch, opto interrupter, optical switch, opticalinterrupter, photo switch, photo interrupter, led display, vacuumfluorescent display, cathode ray tube, liquid crystal display (preformedcharacters, dot matrix, passive matrix, active matrix TFT, flexibledisplay, organic LCD, monochrome LCD, color LCD), diode, triode,tetrode, pentode, hexode, pentagrid, octode, barretter, nuvistor,compactron, microwave, klystron, magnetron, multiple electroniccomponents assembled in a device that is in itself used as a component,oscillator, display device, filter, antennas, elemental dipole,biconical, yagi, phased array, magnetic dipole (loop), wire-wrap,breadboard, enclosure, heat sink, heat sink paste & pads, fan, printedcircuit boards, lamp, memristor, integrated circuit, processor, memory,driver, and electrical leads and interconnects.

In another embodiment, the electrical component comprises organiccomponents. In one embodiment, at least one electrical component isformed on the lightguide, on a component of the lightguide, or on alayer physically coupled to the lightguide material using roll-to-rollprocessing. In a further embodiment, a flexible lightguide film materialis physically coupled to at least one flexible electrical component or acollection of electrical components such that the resulting lightguideis flexible and has can emit light without temporary or permanentvisible demarcation, crease, luminance non-uniformity, MURA, or blemishwhen a light emitting region is bent to a radius of curvature less thanone selected from the group: 100 millimeters, 75 millimeters, 50millimeters, 25 millimeters, 10 millimeters and 5 millimeters.

Light Redirecting Element Disposed to Redirect Light from the Lightguide

In one embodiment, a light emitting device comprises a lightguide withlight redirecting elements disposed on or within the lightguide andlight extraction features disposed in a predetermined relationshiprelative to one or more light redirecting elements. In anotherembodiment, a first portion of the light redirecting elements aredisposed above a light extraction feature in a direction substantiallyperpendicular to the light emitting surface, lightguide, or lightguideregion. In a further embodiment, light redirecting elements are disposedto redirect light which was redirected from a light extraction featuresuch that the light exiting the light redirecting elements is oneselected from the group: more collimated than a similar lightguide witha substantially planar surface; has a full angular width at half maximumintensity less than 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20degrees, 10 degrees, or 5 degrees in a first light output plane; has afull angular width at half maximum intensity less than 60 degrees, 50degrees, 40 degrees, 30 degrees, 20 degrees, 10 degrees, or 5 degrees ina first light output plane and second light output plane orthogonal tothe first output plane; and has a full angular width at half maximumintensity less than 60 degrees, 50 degrees, 40 degrees, 30 degrees, 20degrees, 10 degrees, or 5 degrees in all planes parallel to the opticalaxis of the light emitting device.

In one embodiment, the lightguide comprises a substantially linear arrayof lenticules disposed on at least one surface opposite a substantiallylinear array of light extraction features wherein the light redirectingelement collimates a first portion of the light extracted from thelightguide by the light extraction features. In a further embodiment, alight emitting device comprises a lenticular lens film lightguidefurther comprising coupling lightguides, wherein the couplinglightguides are disposed substantially parallel to the lenticules at thelightguide region or light mixing region and the lenticular lens filmfurther comprises linear regions of light reflecting ink lightextraction features disposed substantially opposite the lenticules onthe opposite surface of the lenticular lens film lightguide and thelight exiting the light emitting device is collimated. In a furtherembodiment, the light extraction features are light redirecting features(such as TIR grooves or linear diffraction gratings) that redirect lightincident within one plane significantly more than light incident from aplane orthogonal to the first. In one embodiment, a lenticular lens filmcomprises grooves on the opposite surface of the lenticules oriented ata first angle greater than 0 degrees to the lenticules.

In another embodiment, a light emitting device comprises a microlensarray film lightguide with an array of microlenses on one surface andthe film further comprises regions of reflecting ink light extractionfeatures disposed substantially opposite the microlenses on the oppositesurface of the lenticular lens film lightguide and the light exiting thelight emitting device is substantially collimated or has an angular FWHMluminous intensity less than 60 degrees. A microlens array film, forexample can collimate light from the light extraction features inradially symmetric directions. In one embodiment, the microlens arrayfilm is separated from the lightguide by an air gap.

The width of the light extraction features (reflecting line of ink inthe aforementioned lenticular lens lightguide film embodiment) willcontribute to the degree of collimation of the light exiting the lightemitting device. In one embodiment, light redirecting elements aredisposed substantially opposite light extraction features and theaverage width of the light extraction features in first directiondivided by the average width in a first direction of the lightredirecting elements is less than one selected from the group: 1, 0.9,0.7, 0.5, 0.4, 0.3, 0.2, and 0.1. In a further embodiment, the focalpoint of collimated visible light incident on a light redirectingelement in a direction opposite from the surface comprising the lightextraction feature is within at most one selected from the group: 5%,10%, 20%, 30%, 40%, 50% and 60% of the width of light redirectingelement from the light extraction feature. In another embodiment, thefocal length of at least one light redirecting element or the averagefocal length of the light redirecting elements when illuminated bycollimated light from the direction opposite the lightguide is less thanone selected from the group: 1 millimeter, 500 microns, 300 microns, 200microns, 100 microns, 75 microns, 50 microns and 25 microns.

In one embodiment, the focal length of the light redirecting elementdivided by the width of the light redirecting element is less than oneselected from the group: 3, 2, 1.5, 1, 0.8, and 0.6. In anotherembodiment, the f/# of the light redirecting elements is less than oneselected from the group: 3, 2, 1.5, 1, 0.8, and 0.6. In anotherembodiment, the light redirecting element is a linear Fresnel lens arraywith a cross-section of refractive Fresnel structures. In anotherembodiment, the light redirecting element is a linear Fresnel-TIR hybridlens array with a cross-section of refractive Fresnel structures andtotally internally reflective structures.

In a further embodiment, light redirecting elements are disposed toredirect light which was redirected from a light extraction feature suchthat a portion of the light exiting the light redirecting elements isredirected with an optical axis at an angle greater than 0 degrees fromthe direction perpendicular to the light emitting region, lightguideregion, lightguide, or light emitting surface. In another embodiment,the light redirecting elements are disposed to redirect light which wasredirected from a light extraction feature such that the light exitingthe light redirecting elements is redirected to an optical axissubstantially parallel to the direction perpendicular to the lightemitting region, lightguide region, lightguide, or light emittingsurface. In a further embodiment, the light redirecting elementdecreases the full angular width at half maximum intensity of the lightincident on a region of the light redirecting element and redirects theoptical axis of the light incident to a region of the light redirectingelement at a first angle to a second angle different than the first.

In another embodiment, the angular spread of the light redirected by thelight extraction feature is controlled to optimize a light controlfactor. One light control factor is the percentage of light reaching aneighboring light redirecting element which could redirect light into anundesirable angle. This could cause side-lobes or light output intoundesirable areas. For example, a strongly diffusively reflectivescattering light extraction feature disposed directly beneath alenticule in a lenticular lens array may scatter light into aneighboring lenticule such that there is a side lobe of light at higherangular intensity which is undesirable in an application desiringcollimated light output. Similarly, a light extraction feature whichredirects light into a large angular rage such as a hemispherical domewith a relatively small radius of curvature may also redirect light intoneighboring lenticules and create side-lobes. In one embodiment, theBidirectional Scattering Distribution Function (BSDF) of the lightextraction feature is controlled to direct a first portion of incidentlight within a first angular range into a second angular range into thelight redirecting element to create a predetermined third angular rangeof light exiting the light emitting device.

Off-Axis Light Redirection

In a further embodiment, at least one light extraction feature iscentered in a first plane off-axis from the axis of the lightredirecting element. In this embodiment, a portion of the lightextraction feature may intersect the optical axis of the lightextraction feature or it may be disposed sufficiently far from theoptical axis that it does not intersect the optical axis of the lightextraction feature. In another embodiment, the distance between thecenters of the light extraction features and the corresponding lightredirecting elements in first plane varies across the array orarrangement of light redirecting elements.

In one embodiment, the locations of the light extraction featuresrelative to the locations of the corresponding light redirectingelements varies in at least a first plane and the optical axis of thelight emitted from different regions of the light emitting surfacevaries relative to the orientation of the light redirecting elements. Inthis embodiment, for example, light from two different regions of aplanar light emitting surface can be directed in two differentdirections. In another example of this embodiment, light from twodifferent regions (the bottom and side regions, for example) of a lightfixture with a convex curved light emitting surface directed downwardsis directed in the same direction (the optical axes of each region aredirected downwards toward the nadir wherein the optical axis of thelight redirecting elements in the bottom region are substantiallyparallel to the nadir, and the optical axis of the light redirectingelements in the side region are at an angle, such as 45 degrees, fromthe nadir). In another embodiment, the locations of the light extractionfeatures are further from the optical axes of the corresponding lightredirecting elements in the outer regions of the light emitting surfacein a direction perpendicular to lenticules than the central regionswhere the light extraction regions are substantially on-axis and thelight emitted from the light emitting device is more collimated.Similarly, if the light extraction features are located further from theoptical axes of the light redirecting elements in a direction orthogonalto the lenticules from a first edge of a light emitting surface, thelight emitted from the light emitting surface can be directedsubstantially off-axis. Other combinations of locations of lightextraction features relative to light redirecting elements can readilybe envisioned including varying the distance of the light extractionfeatures from the optical axis of the light redirecting element in anonlinear fashion, moving closer to the axis then further from the axisthen closer to the axis in a first direction, moving further from theaxis then closer to the axis then further to the axis in a firstdirection, upper and lower apexes of curved regions of a light emittingsurface with a sinusoidal-like cross-sectional (wave-like) profilehaving light extraction features substantially on-axis and the walls ofthe profile having light extraction features further from the opticalaxis of the light redirecting elements, regular or irregular variationsin separation distances of the light extraction features from theoptical axes of the light redirecting elements, etc.

Angular Width Control

In one embodiment, the widths of the light extraction features relativeto the corresponding widths of the light redirecting elements varies inat least a first plane and the full angular width at half maximumintensity of the light emitted from the light redirecting elementsvaries in at least a first plane. For example, in one embodiment, alight emitting device comprises a lenticular lens array lightguide filmwherein the central region of the light emitting surface in a directionperpendicular to the lenticules comprises light extraction features thathave an average width of approximately 20% of the average width of thelenticules and the outer region of the light emitting surface in adirection perpendicular to the lenticules comprises light extractionfeatures with an average width of approximately 5% of the average widthof the lenticules and the angular full width at half maximum intensityof the light emitted from the central region is larger than that fromthe outer regions.

Off-Axis and Angular Width Control

In one embodiment, the locations and widths of the light extractionfeatures relative to the corresponding locations and widths,respectively, of the light redirecting elements varies in at least afirst plane and the full angular width at half maximum intensity of thelight emitted from the light redirecting elements and the optical axisof the light emitted from different regions of the light emittingsurface varies in at least a first plane. By controlling the relativewidths and locations of the light extraction features, the direction andangular width of the light emitted from the light emitting device can bevaried and controlled to achieve desired light output profiles.

Light Redirecting Element

As used herein, the light redirecting element is an optical elementwhich redirects a portion of light of a first wavelength range incidentin a first angular range into a second angular range different than thefirst. In one embodiment, the light redirecting element comprises atleast one element selected from the group: refractive features, totallyinternally reflected feature, reflective surface, prismatic surface,microlens surface, diffractive feature, holographic feature, diffractiongrating, surface feature, volumetric feature, and lens. In a furtherembodiment, the light redirecting element comprises a plurality of theaforementioned elements. The plurality of elements may be in the form ofa 2-D array (such as a grid of microlenses or close-packed array ofmicrolenses), a one-dimensional array (such as a lenticular lens array),random arrangement, predetermined non-regular spacing, semi-randomarrangement, or other predetermined arrangement. The elements maycomprise different features, with different surface or volumetricfeatures or interfaces and may be disposed at different thicknesseswithin the volume of the light redirecting element, lightguide, orlightguide region. The individual elements may vary in the x, y, or zdirection by at least one selected from the group: height, width,thickness, position, angle, radius of curvature, pitch, orientation,spacing, cross-sectional profile, and location in the x, y, or z axis.

In one embodiment, the light redirecting element is optically coupled tothe lightguide in at least one region. In another embodiment, the lightredirecting element, film, or layer comprising the light redirectingelement is separated in a direction perpendicular to the lightguide,lightguide region, or light emitting surface of the lightguide by an airgap. In a further embodiment, the lightguide, lightguide region, orlight emitting surface of the lightguide is disposed substantiallybetween two or more light redirecting elements. In another embodiment, acladding layer or region is disposed between the lightguide orlightguide region and the light redirecting element. In anotherembodiment, the lightguide or lightguide region is disposed between twolight redirecting elements wherein light is extracted from thelightguide or lightguide region from both sides and redirected by lightredirecting elements. In this embodiment, a backlight may be designed toemit light in opposite directions to illuminate two displays, or thelight emitting device could be designed to emit light from one side ofthe lightguide by adding a reflective element to reflect light emittedout of the lightguide in the opposite direction back through thelightguide and out the other side.

In another embodiment, the average or maximum dimension of an element ofa light redirecting element in at least one output plane of the lightredirecting element is equal to or less than one selected from thegroup: 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10% the averageor maximum dimension of a pixel or sub-pixel of a spatial lightmodulator or display. In another embodiment, a backlight comprises lightredirecting elements that redirect light to within a FWHM of 30 degreestoward a display wherein each pixel or sub-pixel of the display receiveslight from two or more light redirecting elements.

In a further embodiment, the light redirecting element is disposed toreceive light from an electro-optical element wherein the opticalproperties may be changed in one or more regions, selectively or as awhole by applying a voltage or current to the device. In one embodiment,the light extraction features are regions of a polymer dispersed liquidcrystal material wherein the light scattering from the lightguide in adiffuse state is redirected by the light redirecting element. In anotherembodiment, the light extraction feature has a small passive region anda larger active region disposed to change from substantially clear tosubstantially transmissive diffuse (forward scattering) such that whenused in conjunction with the light redirecting element, the display canbe changed from a narrow viewing angle display to a larger viewing angledisplay through the application or removal of voltage or current fromthe electro-optical region or material. For example, lines of groovedlight extraction features are disposed adjacent (x, y, or z direction) afilm comprising wider lines polymer dispersed liquid crystal (PDLC)material disposed to change from substantially clear to substantiallydiffuse upon application of a voltage across the electrodes. Otherelectro-optical materials such as electrophoretic, electro-wetting,electrochromic, liquid crystal, electroactive, MEMS devices, smartmaterials and other materials that can change their optical propertiesthrough application of a voltage, current, or electromagnetic field mayalso be used.

In another embodiment, the light redirecting element is a collection ofprisms disposed to refract and totally internally reflect light towardthe spatial light modulator. In one embodiment, the collection of prismsis a linear array of prisms with an apex angle between 50 degrees and 70degrees. In another embodiment, the collection of prisms is a lineararray of prisms with an apex angle between 50 degrees and 70 degrees towhich a light transmitting material has been applied or disposed betweenthe prisms and the lightguide or lightguide region within regions suchthat the film is effectively planarized in these regions and thecollection of prisms is now two-dimensionally varying arrangement ofprisms (thus on the surface it no longer appears to be a linear array).Other forms of light redirecting elements, reverse prisms, hybridelements, with refractive or totally internally reflective features, ora combination thereof, may be used in an embodiment. Modifications ofelements such as “wave-like” variations, variations in size, dimensions,shapes, spacing, pitch, curvature, orientation and structures in the x,y, or z direction, combining curved and straight sections, etc. areknown in the art. Such elements are known in the area of backlights andoptical films for displays and include those disclosed in “Optical filmto enhance cosmetic appearance and brightness in liquid crystaldisplays,” Lee et al., OPTICS EXPRESS, 9 Jul. 2007, Vol. 15, No. 14, pp.8609-8618; “Hybrid normal-reverse prism coupler for light-emitting diodebacklight systems,” Aoyama et al., APPLIED OPTICS, 1 Oct. 2006, Vol. 45,No. 28, pp. 7273-7278; Japanese Patent Application No. 2001190876,“Optical Sheet,” Kamikita Masakazu; U.S. patent application Ser. No.11/743,159; and U.S. Pat. Nos. 7,085,060, 6,545,827, 5,594,830,6,151,169, 6,746,130, and 5,126,882.

Backlight or Frontlight

In one embodiment, a light emitting display backlight or frontlightcomprises a light source, a light input coupler, and a lightguide. Inone embodiment, the frontlight or backlight illuminates a display orspatial light modulator selected from the group: liquid crystal displays(LCD's), MEMs based display, electrophoretic displays, cholestericdisplay, time-multiplexed optical shutter display, color sequentialdisplay, interferometric modulator display, bistable display, electronicpaper display, LED display, TFT display, OLED display, carbon nanotubedisplay, nanocrystal display, head mounted display, head-up display,segmented display, passive matrix display, active matrix display,twisted nematic display, in-plane switching display, advanced fringefield switching display, vertical alignment display, blue phase modedisplay, zenithal bistable device, reflective LCD, transmissive LCD,electrostatic display, electrowetting display, bistable TN displays,micro-cup EPD displays, grating aligned zenithal display, photoniccrystal display, electrofluidic display, and electrochromic displays.

LCD Backlight or Frontlight

In one embodiment, a backlight or frontlight suitable for use with aliquid crystal display panel comprises at least one light source, lightinput coupler, and lightguide. In one embodiment, the backlight orfrontlight comprises a single lightguide wherein the illumination of theliquid crystal panel is white. In another embodiment, the backlight orfrontlight comprises a plurality of lightguides disposed to receivelight from at least two light sources with two different color spectrasuch that they emit light of two different colors. In anotherembodiment, the backlight or frontlight comprises a single lightguidedisposed to receive light from at least two light sources with twodifferent color spectra such that they emit light of two differentcolors. In another embodiment, the backlight or frontlight comprises asingle lightguide disposed to receive light from a red, green and bluelight source. In one embodiment, the lightguide comprises a plurality oflight input couplers wherein the light input couplers emit light intothe lightguide with different wavelength spectrums or colors. In anotherembodiment, light sources emitting light of two different colors orwavelength spectrums are disposed to couple light into a single lightinput coupler. In this embodiment, more than one light input coupler maybe used and the color may be controlled directly by modulating the lightsources.

In a further embodiment, the backlight or frontlight comprises alightguide disposed to receive light from a blue or UV light emittingsource and further comprises a region comprising a wavelength conversionmaterial such as a phosphor film. In another embodiment, the backlightcomprises 3 layers of film lightguides wherein each lightguideilluminates a display with substantially uniform luminance when thecorresponding light source is turned on. In this embodiment, the colorgamut can be increased by reducing the requirements of the color filtersand the display can operate in a color sequential mode or all-colors-onsimultaneously mode. In a further embodiment, the backlight orfrontlight comprises 3 layers of film lightguides with 3 spatiallydistinct light emitting regions comprising light extraction featureswherein each light extraction region for a particular lightguidecorresponds to a set of color pixels in the display. In this embodiment,by registering the light extracting features (or regions) to thecorresponding red, green, and blue pixels (for example) in a displaypanel, the color filters are not necessarily needed and the display ismore efficient. In this embodiment, color filters may be used, however,to reduce crosstalk.

In a further embodiment, the light emitting device comprises a pluralityof lightguides (such as a red, green and blue lightguide) disposed toreceive light from a plurality of light sources emitting light withdifferent wavelength spectrums (and thus different colored light) andemit the light from substantially different regions corresponding todifferent colored sub-pixels of a spatial light modulator (such as anLCD panel), and further comprises a plurality of light redirectingelements disposed to redirect light from the lightguides towards thespatial light modulator. For example, each lightguide may comprise acladding region between the lightguide and the spatial light modulatorwherein light redirecting elements such as microlenses are disposedbetween the light extraction features on the lightguide and the spatiallight modulator and direct the light toward the spatial light modulatorwith a FWHM of less than 60 degrees, a FWHM of less than 30 degrees, anoptical axis of emitted light within 50 degrees from the normal to thespatial light modulator output surface, an optical axis of emitted lightwithin 30 degrees from the normal to the spatial light modulator outputsurface, or an optical axis of emitted light within 10 degrees from thenormal to the spatial light modulator output surface. In a furtherembodiment, an arrangement of light redirecting elements are disposedwithin a region disposed between the plurality of lightguides and thespatial light modulator to reduce the FWHM of the light emitted from theplurality of lightguides. The light redirecting elements arranged withina region, such as on the surface of a film layer, may have similar ordissimilar light redirecting features. In one embodiment, the lightredirecting elements are designed to redirect light from lightextraction features from a plurality of lightguides into FWHM angles oroptical axes within 10 degrees of each other. For example, a backlightcomprising a red, green, and blue film-based lightguides may comprise anarray of microlenses with different focal lengths substantially near the3 depths of the light extraction features on the 3 lightguides. In oneembodiment, lightguide films less than 100 microns thick enable lightredirecting elements to be closer to the light extraction features onthe lightguide and therefore capture more light from the lightextraction feature. In another embodiment, a light redirecting elementsuch as a microlens array with substantially the same light redirectionfeatures (such as the same radius of curvature) may be used with thinlightguides with light extraction features at different depths since thedistance between the nearest corresponding light extraction feature andfarthest corresponding light extraction feature in the thicknessdirection is small relative to the diameter (or a dimension) of thelight redirecting element, pixel, or sub-pixel.

In one embodiment a color sequential display comprises at least onelight source, light input coupler, lightguide and a display panelwherein the panel has a refresh rate faster than one selected from thegroup: 150 hz, 230 hz, 270 hz, 350 hz, 410 hz, 470 hz, 530 hz, 590 hz,650 hz, and 710 hz.

In another embodiment, a backlight or frontlight comprises at least onelight source, light input coupler, and lightguide wherein lightguidecomprises core regions that are substantially thinner than the film andare printed onto a film such that the color or flux of the lightreaching light extracting regions can be controlled.

In another embodiment, a backlight or frontlight comprises at least onelight source, light input coupler, and lightguide wherein lightguideforms a substrate or protective region within the display panel. In oneembodiment, the lightguide is the substrate for the liquid crystaldisplay. In a further embodiment, the lightguide is optically coupled toan outer surface of the display, is disposed within the display, withinthe liquid crystal cell, or between two substrates of the display.

In another embodiment, a backlight or frontlight comprises at least onelight source and a light input coupler comprising at least one couplinglightguide optically coupled to at least one display component (such asa substrate, film, glass, polymer or other layer of a liquid crystalbased display or other display) wherein the component guides lightreceived from the at least one coupling lightguide in a waveguidecondition. By optically coupling the coupling lightguides to a displaycomponent such as an LCD glass substrate for example, the component canfunction as the lightguide and alleviate the need for additionalbacklighting films or components.

In another embodiment, a light emitting device comprises more than onelightguide or lightguide region to provide redundancy of light output incase of difficulties with one backlight or for increased light output.In military and critical display applications (surgery rooms) one oftendesires to have redundancy in case of electrical or light source orother component failure. The reduced thickness of the film-basedlightguide in embodiments allow for one or more additional backlightswhich may include more than one additional light source and driver andelectronic control circuitry. In a further embodiment, one or morephotodetectors such as silicon photodiodes or LEDs used in “reversemode” detects the light intensity (or color) of the light within aregion to determine if the redundant lightguide, color compensationlightguide, or high brightness backlight lightguide should be turned on.In another embodiment, multiple LEDs driven from the same or differentcircuits may be used at the same or different light input couplers toprovide redundancy (or color compensation, or high brightness mode)within a single light input coupler or redundancy through multiple lightinput couplers within the same lightguide. When using multiple lightinput couplers on the same lightguide, the couplers may be arranged onthe same side, the opposite side, an orthogonal side, or at an edgedifferent to the first light input coupler.

Modes of the Light Emitting Device

In another embodiment, a light emitting device comprises one or moremodes selected from the group: normal viewing mode, daytime viewingmode, high brightness mode, low brightness mode, nighttime viewing mode,night vision or NVIS compatible mode, dual display mode, monochromemode, grayscale mode, transparent mode, full color mode, high colorgamut mode, color corrected mode, redundant mode, touchscreen mode, 3Dmode, field sequential color mode, privacy mode, video display mode,photo display mode, alarm mode, nightlight mode, emergency lighting/signmode. The daytime viewing mode may include driving the device (such as adisplay or light fixture) at a high brightness (greater than 300 Cd/m2for example) and may include using two or more lightguides, two or morelight input couplers, or driving additional LEDs at one or more lightinput couplers to produce the increase in brightness. The nighttimeviewing mode may include driving the device at a low brightness (lessthan 50 Cd/m2 for example). The dual display mode may comprise abacklight wherein the lightguide illuminates more than one spatial lightmodulator or display. For example, in a cellphone where there are twodisplays in a flip configuration, each display can be illuminated by thesame film lightguide that emits light toward each display. In atransparent mode, the lightguide may be designed to be substantiallytransparent such that one can see through the display or backlight. Inanother embodiment, the light emitting device comprises at least onelightguide for a first mode, and a second backlight for a second modedifferent than the first mode. For example, the transparent modebacklight lightguide on a device may have a lower light extractionfeature density, yet enable see-through. For a high brightness mode onthe same device, a second lightguide may provide increased displayluminance relative to the transparent mode. The increased color gamutmode, may provide an increased color gamut (such as greater than 100%NTSC) by using one or more spectrally narrow colored LEDs or lightsources. These LEDs used in the high color gamut mode may provideincreased color gamut by illumination through the same or differentlightguide or light input coupler. The color corrected mode maycompensate for light source color variation over time (such as phosphorvariation), LED color binning differences, or due to temperature or theenvironment. The touchscreen mode may allow one or more lightguides tooperate as an optical frustrated TIR based touchscreen. The redundantbacklight mode may comprise one or more lightguides or light sourcesthat can operate upon failure or other need. The 3D mode for the lightemitting device may comprise a display and light redirecting elements ora display and polarization based, LC shutter based, or spectrallyselective based glasses to enable stereoscopic display. The mode may,for example, comprise one or more separate film-based backlightlightguide for 3D mode or a film-based lightguide and a displayconfigured to display images stereoscopically. The privacy mode, forexample, may comprise a switchable region of a polymer dispersed liquidcrystal disposed beneath a light redirecting element to increase ordecrease the viewing angle by switching to a substantially diffuse mode,or substantially clear mode, respectively. In another embodiment, thelight emitting device further comprises a video display mode or a photodisplay mode wherein the color gamut is increased in the mode. In afurther embodiment, the light emitting device comprises an alarm modewherein one or more lightguides is turned on to draw attention to aregion or a display. For example, when a cellphone is ringing, thelightguide that is formed around or on a portion of the exterior of thecellphone may be illuminated to “light up” the phone when it is ringing.By using a film-based lightguide, the lightguide film may be formed intoa phone housing (thermoforming for example) or it may be film-insertmolded to the interior (translucent or transparent housing) or exteriorof the housing. In another embodiment, the light emitting device has anemergency mode wherein at least one lightguide is illuminated to providenotification (such as displaying the illuminated word “EXIT”) orillumination (such as emergency lighting for a hallway). Theillumination in one or more modes may be a different color to provideincreased visibility through smoke (red for example).

NVIS Compatible Mode

The night vision or NVIS mode may include illuminating one or morelightguides, two or more light input couplers, or driving additionalLEDs at one or more light input couplers to produce the desiredluminance and spectral output. In this mode, the spectrum of the LEDsfor an NVIS mode may be compatible with US Military specificationsMIL-STD-3009, for example. In applications requiring an NVIS compatiblemode, a combination of LEDs or other light sources with different colorsmay be used to achieve the desired color and compatibility in a daytimemode and nighttime mode. For example, a daytime mode may incorporatewhite LEDs and blue LEDs, and a nighttime or NVIS mode may incorporatewhite, red, and blue LEDs where the relative output of one or more ofthe LEDs can be controlled. These white or colored LEDs may be disposedon the same light input coupler or different light input couplers, thesame lightguide or different lightguides, on the same side of thelightguide, or on a different side of the lightguide. Thus, eachlightguide may comprise a single color or a mixture of colors andfeedback mechanisms (such as photodiodes or LEDs used in reverse mode)may be used to control the relative output or compensate for colorvariation over time or background (ambient) lighting conditions. Thelight emitting device may further comprise an NVIS compatible filter tominimize undesired light output, such as a white film-based backlightlightguide with a multilayer dielectric NVIS compatible filter where thewhite lightguide is illuminated by white LEDs or white LEDs and RedLEDs. In a further embodiment, a backlight comprises one or morelightguides illuminated by light from one or more LEDs of color selectedfrom the group: red, green, blue, warm white, cool white, yellow, andamber. In another embodiment, the aforementioned backlight furthercomprises a NVIS compatible filter disposed between the backlight orlightguide and a liquid crystal display.

Field Sequential Color Mode

In a further embodiment, a backlight or frontlight comprises alightguide comprising light extraction features and a light redirectingelement disposed to receive a portion of the light extracted from thelightguide and direct a portion of this light into a predeterminedangular range. In another embodiment, the light redirecting elementsubstantially collimates, reduces the angular full-width at half maximumintensity to 60 degrees, reduces the angular full-width at half maximumintensity to 30 degrees, reduces the angular full-width at half maximumintensity to 20 degrees, or reduces the angular full-width at halfmaximum intensity to 10 degrees, a portion of light from the lightguideand reduces the percentage of cross-talk light from one light extractionregion reaching an undesired neighboring pixel, sub-pixel, or colorfilter. When the relative positions of the light extraction features,light redirecting elements, and pixels, sub-pixels, or color filters arecontrolled then light from a predetermined light extraction feature canbe controlled such that there is little leakage of light into aneighboring pixel, sub-pixel, or color filter. This can be useful in abacklight or frontlight such as a color sequential backlight whereinthree lightguides (one for red, green, and blue) extract light in apattern such that color filters are not needed (or color filters areincluded and the color quality, contrast or gamut is increased) sincethe light is substantially collimated and no light or a small percentageof light extracted from the lightguide by a light extraction feature onthe red lightguide beneath a pixel corresponding to a red pixel will bedirected into the neighboring blue pixel.

Stereoscopic Display Mode

In another embodiment, a display capable of operating in stereoscopicdisplay mode comprises a backlight or frontlight wherein at least onelightguide or light extracting region is disposed within or on top of afilm-based lightguide wherein at least two sets of light emittingregions can be separately controlled to produce at least two sets ofimages in conjunction with a stereoscopic display. The 3D display mayfurther comprise light redirecting elements, parallax barriers,lenticular elements, or other optical components to effectively convertthe spatially separated light regions into angularly separated lightregions either before or after spatially modulating the light.

In a further embodiment, a light emitting device comprises at least onefirst lightguide emitting light in a first angular range and at leastone second lightguide emitting light in a second angular range. Byemploying lightguides emitting lightguides emitting light into twodifferent angular ranges, viewing angle dependent properties such asdual view display or stereoscopic display or backlight can be created.In one embodiment, the first lightguide emits light with an optical axissubstantially near +45 degrees from the normal to the light outputsurface and the second lightguide emits light with an optical axissubstantially near −45 degrees from the normal to the light outputsurface. For example, a display used in an automobile display dashbetween the driver and passenger may display different information toeach person, or the display may more efficiently direct light toward thetwo viewers and not waste light by directing it out normal to thesurface. In a further embodiment, the first lightguide emits lightcorresponding to light illuminating first regions of a display (or afirst time period of the display) corresponding to a left image and thesecond lightguide emits light corresponding to light illuminating secondregions of a display (or a second time period of the display)corresponding to a right image such that the display is a stereoscopic3D display.

In one embodiment, the first lightguide emits substantially white lightin a first angular direction from a first set of light extractionfeatures and a second light guide beneath the first lightguide emitssubstantially white light in a second angular direction from a secondset of light extraction features. In another embodiment, the first setof light extraction features are disposed beneath a first set of pixelscorresponding to a left display image and the second set of lightextraction features are substantially spatially separated from the firstand disposed beneath a second set of pixels corresponding to a rightdisplay image and the display is autostereoscopic. In a furtherembodiment, the aforementioned autostereoscopic display furthercomprises a third lightguide emitting light toward the first and secondsets of pixels and is illuminated in a 2D display mode display fullresolution.

Field Sequential Color & Stereoscopic Mode

One or more lightguides may be illuminated by red, green, and blue (andoptionally other colors for increased color gamut such as yellow) lightwhich may illuminate a spatial light modulator in a Field SequentialColor (FSC) or Color Sequential (CS) mode. In addition, the display maybe driven in a fast mode such that when synchronized with liquid crystalbased shutter glasses, the display appears 3D through stereoscopicdisplay. Other methods such as passive polarizer (linear or circular)based viewing glasses and interference filter spectrally selective 3Dmethods (such as used by Dolby 3D) may also be employed with a fieldsequential color based backlight comprising a film-based lightguide. Inanother embodiment, the lightguides may be driven sequentially or thelight sources illuminating separate lightguides may be drivensequentially. In one embodiment, one or more light sources illuminatinga first lightguide are pulsed on, followed by pulsing on one or morelight sources illuminating a second lightguide, then pulsing one or morelight sources in the first lightguide. Multiple lightguides, spatialregions of one or more lightguides, or spectrally selected elementswithin the lightguides may be used in a color sequential display toincrease the color gamut, decrease the percentage of light absorbed bythe color filters, or eliminate the color filters. In anotherembodiment, two separate lightguides are illuminated with red, green,and blue light and the lightguides have two spatially separate regionscomprising light extraction features wherein the light emitting devicefurther comprises a light redirecting element which redirects light fromthe first lightguide into a first angular range corresponding to theleft image and further redirects light from the second lightguide into asecond angular range corresponding to the right image and a liquidcrystal panel driven to display stereoscopic information in a spatialconfiguration and the display is a autostereoscopic 3D display. In afurther embodiment, two separate lightguides are illuminated with red,green and blue light and the lightguides have two spatially separate oroverlapping regions comprising light extraction features wherein thelight emitting device further comprises a liquid crystal panel driven ata frequency higher than 100 hz to display stereoscopic information suchthat a stereoscopic display is visible with liquid crystal shutter basedglasses. In a further embodiment, the red, green, and blue light emittedfrom the first backlight have wavelength spectrums R1, G1, and B1,respectively, and the red, green, and blue light emitted from the secondbacklight have wavelength spectrums R2, G2, and B2, respectively and R1does not substantially overlap R2, G1 does not substantially overlap G2,and B1 does not substantially overlap B2, and spectrally selectiveviewing glasses may be used to view the display in stereoscopic 3D suchas those disclosed in embodiments of stereoscopic viewing systems inU.S. Pat. Application Nos. US20090316114, US20100013911, US20100067108,US20100066976, US20100073769, and US2010006085.

Table 1 illustrates examples of embodiments comprising one or morelightguides, one or more colored sources, 3D driving techniques andpixel arrangements for 2D and 3D displays.

TABLE 1 Example modes for driving 2D & 3D displays under embodimentsLight extraction feature Two Angular Pixel Light source modulationLightguides pattern outputs Arrangement Continuous 1 White Standard NoStandard Continuous 1 White Standard No Standard Continuous 2 WhiteSpatially separate L&R Yes Standard + (L&R images) Continuous 1 R + G +B Standard No Standard Continuous 1 R + G + B Standard No StandardContinuous 2 × R + G + B Spatially separate L&R Yes Standard + (L&Rimages) Continuous 3 (R, G, & B) Standard No Standard Continuous 3 (R,G, & B) Standard No Standard Continuous 3 (R, G, & B) Separate regionsfor R, G, & B No Standard Continuous 3 (R, G, & B) Separate regions forR, G, & B No Standard Source Color Sequential 1 R + G + B Standard NoStandard Source Color Sequential 1 R + G + B Standard No Standard Sourcecolor sequential 3 (R, G, & B) Standard No Standard Source colorsequential 3 (R, G, & B) Standard No Standard Source color sequential 3(R, G, & B) Separate regions for R, G, & B No Standard Source colorsequential 3 (R, G, & B) Separate regions for R, G, & B No StandardLightguide sequential 2 White Standard or adjacent patterns Yes StandardLightguide Sequential 2 × (R + G + B) Standard or adjacent patterns YesStandard Lightguide Sequential 2 White Separate regions for Left & RightNo Standard + L&R images Lightguide Sequential 2 × (R + G + B) Separateregions for Left & Right Yes Standard + L&R images R1, R2, G1, G2, B1,B2, stereoscopic 2 × (R + G + B) Standard No Standard color SequentialR1, R2, G1, G2, B1, B2, stereoscopic 2 × (R + G + B) Separate regionsfor Left & Right No Standard + L&R color Sequential images R1, R2, G1,G2, B1, B2, stereoscopic 2 × (R + G + B) Separate regions for Left &Right Yes Standard + L&R color Sequential images Color Shutter 2D/3DLight source modulation Filters Panel drive scheme Glasses modesContinuous Yes Standard No 2D Continuous Yes Left then right image Yes2D + 3D Continuous Yes Standard + 3D spatial mode No 2D + 3D ContinuousYes Standard No 2D Continuous Yes Left then right image Yes ContinuousYes Standard + 3D spatial mode No 2D + 3D Continuous Yes Standard No 2DContinuous Yes Left then right image Yes 2D + 3D Continuous NoneStandard No 2D Continuous None Left then right image Yes 2D + 3D SourceColor Sequential Optional Color Field Sequential (CFS) No 2D SourceColor Sequential Optional CFS + Left then right image Yes 2D + 3D Sourcecolor sequential No Color Field Sequential No 2D Source color sequentialNo CFS + Left then right image Yes 2D + 3D Source color sequentialOptional Color Field Sequential No 2D Source color sequential OptionalLeft then right image Yes 2D + 3D Lightguide sequential Yes Left thenright image No 2D + 3D Lightguide Sequential Yes Left then right imageNo 2D + 3D Lightguide Sequential Yes Left then right image Yes 2D + 3DLightguide Sequential Yes Left then right image Yes 2D + 3D R1, R2, G1,G2, B1, B2, stereoscopic No Stereoscopic CFS Yes 2D + 3D colorSequential R1, R2, G1, G2, B1, B2, stereoscopic Optional StereoscopicCFS Yes 2D + 3D color Sequential R1, R2, G1, G2, B1, B2, stereoscopicOptional Stereoscopic CFS No 2D + 3D color Sequential

Drive schemes of liquid crystal displays, MEMs-based displays,projection displays, or other displays including Field Sequential Colordrive or Color Sequential drive schemes of one or more embodimentsinclude drive schemes disclosed in U.S. patent application Ser. No.12/124,317, U.S. Pat. Nos. 7,751,663; 7,742,031; 7,742,016; 7,696,968;7,695,180; 7,692,624; 7,731,371; 7,724,220; 7,728,810; 7,728,514; andU.S. Pat. Application Publication Nos. US20100164856; US20100164855;US20100164856; US20100165218; US20100156926; US20100149435;US20100134393; US20100128050; US20100127959; US20100118007;US20100117945; US20100117942; US20100110063; US20100109566;US20100079366; US20100073568; US20100072900; US20100060556;US20100045707; US20100045579; US20100039425; US20100039359;US20100039358; US20100019999; and US20100013755.

In some embodiments shown in Table 1, the display shows information forone image and subsequently shows information for a second image (leftand right images for example). It is understood that regions of thedisplay can display portions of the image for viewing by the left eyewhile a different region of the display simultaneously shows imagescorresponding to the right eye. The display may provide spatial lightmodulation corresponding to a first field of information in a regionfollowed by a second field of information (such as a first framefollowed by a second frame, progressive scanning, interlaced, etc.).Embodiment include standard pixel arrangements and 3D backlight andpixel arrangements such as matrix, RGB Stripes, and PenTile sub-pixelarrangements and other arrangements such as those disclosed in U.S. Pat.Nos. 6,219,025; 6,239,783; 6,307,566; 6,225,973; 6,243,070; 6,393,145;6,421,054; 6,282,327; 6,624,828; 7,728,846; 7,689,058; 7,688,335;7,639,849; 7,598,963; 7,598,961; 7,590,299; 7,589,743; 7,583,279;7,525,526; 7,511,716; 7,505,053; 7,486,304; 7,471,843; 7,460,133;7,450,190; 7,427,734; 7,417,601; 7,404,644; 7,396,130; 7,623,141;7,619,637; and U.S. Pat. Application Publication Nos. US20100118045;US20100149208 US20100096617; US20100091030; US20100045695;US20100033494; US20100026709; US20100026704; US20100013848;US20100007637; US20090303420; US20090278867; US20090278855;US20090262048; US20090244113; US20090081064; US20090081063;US20090071734; US20090046108; US20090040207; US20090033604;US20080284758; US20080278466; US20080266330; and US20080266329.

In one embodiment, the light emitting device emits light toward adisplay with reflective components such that the illumination isdirected toward the spatial light modulating pixels from the viewingside of the pixels. In another embodiment, a display comprises afilm-based light emitting device comprising a light source, light inputcoupler, and lightguide lighting a display from the front wherein thelight extracting regions of the lightguide direct light toward aninterferometric modulator or IMOD such as those disclosed in U.S. Pat.Nos. 6,680,792; 7,556,917; 7,532,377 and 7,297,471. The lightguide maybe a component external to the display, an integral component of thedisplay, or optical coupled to a surface or layer of the display. In oneembodiment, a frontlight comprises a lightguide film comprising a corematerial or cladding material that comprises silicone.

In another embodiment, a display comprises a film-based light emittingdevice comprising a light source, light input coupler, and lightguidelighting a display from the front wherein the light extracting regionsof the lightguide direct light toward at least one selected from thegroup: reflective LCD, electrophoretic display, cholesteric display,zenithal bistable device, reflective LCD, electrostatic display,electrowetting display, bistable TN display, micro-cup EPD display,grating aligned zenithal display, photonic crystal display,electrofluidic display, and electrochromic displays. In anotherembodiment, a display comprises a film-based light emitting devicecomprising a light source, light input coupler, and lightguide lightinga display wherein the light extraction features of the lightguide directlight toward a time-multiplexed optical shutter display such as onedisclosed in U.S. patent application Ser. Nos. 12/050,045; 12/050,032;12/050,045; 11/524,704; 12/564,894; 12/574,700; 12/546,601; 11/766,007and U.S. Pat. Nos. 7,522,354 and 7,450,799.

In one embodiment, the light emitting device comprises a reflectivespatial light modulator disposed between the lightguide and the lightsource for the light emitting device. For example, the lightguide couldbe disposed on the front of an electrophoretic display and at least oneselected from the group: lightguide, lightguide region, light mixingregion, and coupling lightguide could wrap around the electrophoreticdisplay and the light source could be disposed behind the display.

In one embodiment, the lightguide serves as an illuminator for afrustrated total internal reflection type display such as an opticalshutter display that is time-multiplexed by Unipixel Inc. or a MEMs typedisplay with a movable shutter such as displays by Pixtronix Inc. or areflective MEMS based interferometric display such as those fromQualcomm MEMS Technologies.

In another embodiment, a display comprises a film-based light emittingdevice comprising a light source, light input coupler, and lightguideilluminating a display or providing a lightguide for a display toperform light extraction wherein the display or light emitting device isa type disclosed in U.S. patent application Ser. Nos. 12/511,693;12/606,675; 12/221,606; 12/258,206; 12/483,062; 12/221,193; 11/975,41111/975,398; 10/312,003; 10/699,397 or U.S. Pat. Nos. 7,586,560;7,535,611; 6,680,792; 7,556,917; 7,532,377; 7,297,471; 6,680,792;6,865,641; 6,961,175; 6,980,350; 7,012,726; 7,012,732; 7,035,008;7,042,643; 7,046,374; 7,060,895; 7,072,093; 7,092,144; 7,110,158;7,119,945; 7,123,216; 7,130,104; 7,136,213; 7,138,984; 7,142,346;7,161,094; 7,161,728; 7,161,730; 7,164,520; 7,172,915; 7,193,768;7,196,837; 7,198,973; 7,218,438; 7,221,495; 7,221,497; 7,236,284;7,242,512; 7,242,523; 7,250,315; 7,256,922; 7,259,449; 7,259,865;7,271,945; 7,280,265; 7,289,256; 7,289,259; 7,291,921; 7,297,471;7,299,681; 7,302,157; 7,304,784; 7,304,785; 7,304,786; 7,310,179;7,317,568; 7,321,456; 7,321,457; 7,327,510; 7,333,208; 7,343,080;7,345,805; 7,345,818; 7,349,136; 7,349,139; 7,349,141; 7,355,779;7,355,780; 7,359,066; 7,365,897; 7,368,803; 7,369,252; 7,369,292;7,369,294; 7,369,296; 7,372,613; 7,372,619; 7,373,026; 7,379,227;7,382,515; 7,385,744; 7,385,748; 7,385,762; 7,388,697; 7,388,704;7,388,706; 7,403,323; 7,405,852; 7,405,861; 7,405,863; 7,405,924;7,415,186; 7,417,735; 7,417,782; 7,417,783; 7,417,784; 7,420,725;7,420,728; 7,423,522; 7,424,198; 7,429,334; 7,446,926; 7,446,927;7,447,891; 7,450,295; 7,453,579; 7,460,246; 7,460,290; 7,460,291;7,460,292; 7,470,373; 7,471,442; 7,471,444; 7,476,327; 7,483,197;7,486,429; 7,486,867; 7,489,428; 7,492,502; 7,492,503; 7,499,208;7,502,159; 7,515,147; 7,515,327; 7,515,336; 7,517,091; 7,518,775;7,520,624; 7,525,730; 7,526,103; 7,527,995; 7,527,996; 7,527,998;7,532,194; 7,532,195; 7,532,377; 7,532,385; 7,534,640; 7,535,621;7,535,636; 7,542,198; 7,545,550; 7,545,552; 7,545,554; 7,547,565;7,547,568; 7,550,794; 7,550,810; 7,551,159; 7,551,246; 7,551,344;7,553,684; 7,554,711; 7,554,714; 7,556,917; 7,556,981; 7,560,299;7,561,323; 7,561,334; 7,564,612; 7,564,613; 7,566,664; 7,566,940;7,567,373; 7,570,865; 7,573,547; 7,576,901; 7,582,952; 7,586,484;7,601,571; 7,602,375; 7,603,001; 7,612,932; 7,612,933; 7,616,368;7,616,369; 7,616,781; 7,618,831; 7,619,806; 7,619,809; 7,623,287;7,623,752; 7,625,825; 7,626,581; 7,626,751; 7,629,197; 7,629,678;7,630,114; 7,630,119; 7,630,121; 7,636,151; 7,636,189; 7,642,110;7,642,127; 7,643,199; 7,643,202; 7,643,203; 7,643,305; 7,646,529;7,649,671; 7,653,371; 7,660,031; 7,663,794; 7,667,884; 7,668,415;7,675,665; 7,675,669; 7,679,627; 7,679,812; 7,684,104; 7,684,107;7,692,839; 7,692,844; 7,701,631; 7,702,192; 7,702,434; 7,704,772;7,704,773; 7,706,042; 7,706,044; 7,706,050; 7,709,964; 7,710,629;7,710,632; 7,710,645; 7,711,239; 7,715,079; 7,715,080; 7,715,085;7,719,500; 7,719,747; and 7,719,752.

Location of the Film-Based Lightguide Frontlight

In one embodiment, a film-based lightguide frontlight is disposedbetween a touchscreen film and a reflective spatial light modulator. Inanother embodiment, a touchscreen film is disposed between thefilm-based lightguide and the reflective spatial light modulator. Inanother embodiment, the reflective spatial light modulator, thefilm-based lightguide frontlight and the touchscreen are all film-baseddevices and the individual films may be laminated together. In anotherembodiment, the light transmitting electrically conductive coating forthe touchscreen device or the display device is coated onto thefilm-based lightguide frontlight. In a further embodiment, thefilm-based lightguide is physically coupled to the flexible electricalconnectors of the display or the touchscreen. In one embodiment, theflexible connector is a “flexible cable”, “flex cable,” “ribbon cable,”or “flexible harness” comprising a rubber film, polymer film, polyimidefilm, polyester film or other suitable film.

In another embodiment, the film-based lightguide frontlight comprises atleast one of a lightguide region, light mixing region, couplinglightguide or light input coupler adhered to one or more flexibleconnectors and the light input coupler is folded behind the reflectivedisplay. For example, in one embodiment, a flexible film-basedlightguide comprising a polydimethylsiloxane (PDMS) core and a lowrefractive index pressure sensitive adhesive cladding is laminated to apolyimide flexible display connector that connects the display driversto the active display area in a reflective display.

In one embodiment, a light emitting device comprising a film-basedfrontlight and one or more of a light source, coupling lightguide,non-folded coupling lightguide, input coupler housing, alignment guide,light source thermal transfer element, and relative position maintainingelement is physically coupled to a flexible circuit connector or circuitboard physically coupled to a flexible circuit connector for areflective display, touchscreen, or frontlight. For example, in oneembodiment, a light source for the film-based lightguide is disposed onand electrically driven using the same circuit board as the drivers fora reflective display. In another embodiment, the flexible film-basedlightguide comprises the traces, wires, or other electrical connectionsfor the display or frontlight, thus enabling one less flexible connectoras the film-based lightguide provides that function. In anotherembodiment, a light source for the film-based frontlight is physicallycoupled to or shares a common circuit board or flexible circuit with oneor more of the following: a light source driver, display drivertouchscreen driver, microcontroller, additional light source for anindicator, alignment or registration pins, alignment guides, alignmentor registration holes, openings or apertures, heat sink, thermaltransfer element, metal core substrate, light collimating opticalelement, light turning optical element, bi-directional optical element,light coupling optical element, secondary optic, light input coupler,plurality of light input couplers, and light emitting device housing.

In one embodiment, the film-based lightguide is folded around a firstedge of the active area of a reflective spatial light modulator behind areflective spatial light modulator and one or more selected from thegroup: touchscreen connector, touchscreen film substrate, reflectivespatial light modulator connector, and reflective spatial lightmodulator film substrate is folded behind the first edge, a second edgessubstantially orthogonal to the first edge, or an opposite edge to thefirst edge. In the aforementioned embodiment, a portion of thelightguide region, light mixing region, or coupling lightguide comprisesthe bend region of the fold and may extend beyond the reflective spatiallight modulator flexible connector, reflective spatial light modulatorsubstrate, touchscreen flexible connector or touchscreen flexiblesubstrate.

In one embodiment, the film-based lightguide frontlight comprises twolight input couplers disposed along the same or two different sides of aflexible connector, display substrate film, or touchscreen film. Inanother embodiment, a display connector or touchscreen connector isdisposed between two light input couplers of a film-based lightguidefrontlight. In another embodiment, coupling lightguides of a film-basedfrontlight are folded and stacked in an array, aligned in registration(using pins, cavities, or alignment guides, for example) with a lightsource (which may be disposed on the circuit or connector for a displayor touchscreen) and the film-based lightguide is subsequently laminatedto the flexible connectors and/or the reflective display or touchscreen.In another embodiment, the film-based lightguide is laminated to theflexible connectors and/or the reflective display or touchscreen andsubsequently the coupling lightguides of the film-based frontlight arefolded and stacked in an array, and aligned in registration (using pins,cavities, or alignment guides, for example) with a light source (whichmay be disposed on the circuit or connector for a display ortouchscreen). In a further embodiment, the lamination and registrationare performed substantially simultaneously. In a further embodiment, thelight extraction features are formed on (or within) the film-basedlightguide subsequent to laminating (or adhering) onto the touchscreenor spatial light modulator. In this embodiment, the registration oflight extraction regions (or light emitting area) of the film-basedfrontlight (or backlight) with the spatial light modulator does not needto be performed before or during lamination because the features can bereadily registered (such as screen printed, etched, scribed, or laserablated) after the lamination or adhering process.

Flexible Light Emitting Device, Backlight, or Frontlight

In another embodiment, a light emitting device such as a displaycomprises a film-based light emitting device comprising a light source,light input coupler, and lightguide wherein the lightguide, lightguideregion, or coupling lightguides can be bent or folded to radius ofcurvature of less than 75 times the thickness of lightguide orlightguide region and function similarly to similar lightguide orlightguide region that has not been similarly bent. In anotherembodiment, the lightguide, coupling lightguide, or lightguide regioncan be bent or folded to radius of curvature greater than 10 times thetimes the thickness lightguide or lightguide region and functionsimilarly to similar lightguide or lightguide region that has not beensimilarly bent. In another embodiment, a display comprises a film-basedlight emitting device comprising a light source, light input coupler,and lightguide wherein the display can be bent or folded to radius ofcurvature of less than 75 times the thickness of display or lightguideregion and function similarly to similar display that has not beensimilarly bent. In another embodiment, the display is capable of beingbent or folded to radius of curvature greater than 10 times the timesthe thickness lightguide or lightguide region and function similarly tosimilar display that has not been similarly bent.

In one embodiment, the light emitting device or a display incorporatinga light emitting device is bent into a substantially non-planar lightemitting device or display incorporating a light emitting device. In oneembodiment, the light emitting device or display incorporating the lightemitting device has a light emitting surface area substantially in theshape of or comprising a portion of a shape of at least one selectedfrom the group: a cylinder, sphere, pyramid, torus, cone, arcuatesurface, folded surface, and bent surface. By folding the input couplerbehind the light emitting region and inside a curved or bent region ofthe light emitting device or display, the input coupler can beeffectively “hidden” from view and a substantially seamless display canbe created. In another embodiment, two or more regions of a lightemitting region in a light emitting device overlap each other in thethickness direction such that there is a continuous light emittingregion such as in the case of a cylindrical display or a displaywrapping around two or more sides of a rectangular solid.

In another embodiment, the backlight or frontlight is incorporated intoa portable device such as a cellphone, smartphone, personal digitalassistant, laptop, tablet computer, pad computer (such as those fromApple Inc.), ebook, e-reader, or other computing device.

Keypad and Backlight

In another embodiment, a light emitting device provides light as afrontlight or backlight of a display and also illuminates an object. Thelightguide, for example, may extend from the display region to a keypadregion for a laptop or cellphone. In another embodiment, the object ofillumination is one or more selected from the group: a wall or mountableobject to which the display is affixed, the surface of the keys of akeyboard to be pressed, other buttons, and a second display. In anotherembodiment, the light emitting device provides light as a frontlight orbacklight of a display and also provides external white or colorillumination as an illuminating device such as a light fixture orflashlight.

Lightguide is Also a Touchscreen

In one embodiment, the lightguide is also a touchscreen for detectinghaptic feedback, contact, proximity, or location of user input by fingeror stylus or other device. In one embodiment, the lightguide carries atleast one selected from the group: illumination or light modified by theinput as well as providing frontlight, backlight, audio, or otherfunctionality. In one embodiment, the lightguide is an opticaltouchscreen. Optical based touchscreens are known in the art and in oneembodiment, the optical based touchscreen is one disclosed in U.S.patent application Ser. Nos. 11/826,079, 12/568,931, or 12/250,108. Inanother embodiment, the lightguide is an optical touchscreen suitablefor a night vision display or night vision display mode. In a furtherembodiment, the lightguide is a night vision compatible touchscreen asdescribe in U.S. patent application Ser. No. 11/826,236.

In another embodiment, the lightguide is a surface acoustic wave basedtouchscreen such as disclosed in U.S. Pat. Nos. 5,784,054, 6,504,530 orU.S. patent application Ser. No. 12/315,690.

Head-Up Display

In another embodiment, a head-up display comprises a film-based lightemitting device comprising a light source, light input coupler, andlightguide. Head-up displays are used in automobiles, aircraft andmarine craft. In one embodiment, the lightguide of a head-up display isone selected from the group: incorporated into a windshield, an integralpart of a windshield, formed with light extracting features beforebecoming encapsulated within a windshield, formed with light extractingfeatures after becoming encapsulated within a windshield, disposed on aninner or outer surface a windshield, an after-market HUD, afree-standing HUD suitable for placement on an automobile dashboard,formed where the lightguide comprises PVB as a core or claddingmaterial.

Small or Substantially Edgeless Light Emitting Device

In one embodiment, a light emitting device comprises a border regionbetween a light emitting region and the nearest edge of the lightguidein a first direction orthogonal to the direction orthogonal to the lightemitting device output surface near the edge with a region dimension inthe first direction less than one selected from the group: 20millimeters, 10 millimeters, 5 millimeters, 2 millimeters, 1millimeters, and 0.5 millimeters. The border region may be sufficientlysmall such that the light emitting device, backlight, frontlight, lightfixture, or display incorporating the light emitting device appears tobe edgeless or substantially without an edge. The light emitting devicemay have a small border region along, one, two, three, four or moreedges. The border region may comprise a small frame, bevel, housing, orother structure or component. In a further embodiment, a light emittingdevice comprises a film-based lightguide wherein the light emittingregion extends around the edge of the light emitting device frontsurface in a first borderless region such that the light emitting devicedoes not have a border or frame region in the first borderless region.For example, in one embodiment, a light emitting display with asubstantially flat viewing surface comprises a flexible film-basedlightguide wherein a first region of a light emitting region of thelightguide is folded around behind a second region of the light emittingregion such that the light emitting region extends to the edge andaround the edge in at least one region of the display. By combining theflexible film-based lightguide with a flexible spatial light modulatorsuch as a flexible LCD, the display and backlight comprising afilm-based lightguide can bend around a corner or edge of the display.

In one embodiment, a light emitting device comprises at least two arraysof coupling lightguides disposed along one edge or side of a lightemitting device wherein the light within the first array of couplinglightguides is propagating substantially in a first direction and thelight within the second array of coupling lightguides is propagatingsubstantially in a second direction oriented greater than 90 degreesfrom the first direction. In another embodiment, two light sources aredisposed along one side or side of a light emitting device with theiroptical axes oriented in substantially opposite directions to each othersuch that light is coupled into two arrays of coupling lightguides andat neither light source is disposed past the intersection of the edge orside and the adjacent edge or side of the light emitting device. In afurther embodiment, one light source is disposed along one side of alight emitting device disposed to emit light in substantially oppositedirections such that light is coupled into two arrays of couplinglightguides and the light source is not disposed past the intersectionof the edge or side and the adjacent edge or side of the light emittingdevice.

In a further embodiment, the use of one or more light input couplersdisposed to receive light from a light source from a direction orientedaway from the central region of the edge or side of the light emittingdevice allows the adjacent side or edge to have a substantially small oredgeless border region since the light source does not extend past theneighboring edge or border.

In a further embodiment, at least one light input coupler is foldedbehind at least one selected from the group: light mixing region orlight emitting region such that the distance between the edge of thelight emitting region and the light emitting device (the border region)is less than one selected from the group: 20 millimeters, 10millimeters, 5 millimeters, 2 millimeters, 1 millimeters, and 0.5millimeters.

In a further embodiment, a plurality of light input couplers are foldedbehind at the light mixing region and light emitting region such thatthe distance between the edge of the light emitting region and the lightemitting device (the border region) along at least two sides or edges ofthe light emitting device is less than one selected from the group: 20millimeters, 10 millimeters, 5 millimeters, 2 millimeters, 1millimeters, and 0.5 millimeters.

In a further embodiment, a plurality of light input couplers are foldedbehind at least one selected from the group: light mixing region orlight emitting region such that the distance between the edge of thelight emitting region and the light emitting device (the border region)along all of the sides or edges of the light emitting device is lessthan one selected from the group: 20 millimeters, 10 millimeters, 5millimeters, 2 millimeters, 1 millimeters, and 0.5 millimeters. In afurther embodiment, selected from the group: the light input surfacesand/or the coupling lightguides are substantially folded behind at leastone selected from the group: light mixing region and light emittingregion such that the distance between the edge of the light emittingregion and the light emitting device, the border region, along at leastthree sides or edges of the light emitting device is less than oneselected from the group: 20 millimeters, 10 millimeters, 5 millimeters,2 millimeters, 1 millimeters, and 0.5 millimeters.

In another embodiment, a light emitting device comprises at least onelight input coupler disposed along one edge or side with the lightsource disposed within the inner region defined by the region betweenthe two adjacent edges or sides of the light emitting device. In thisembodiment, the light input coupler may be a middle input couplerwherein the light source is disposed substantially in middle region ofthe inner region.

In a further embodiment, at least one portion of the array of couplinglightguides is disposed at a first coupling lightguide orientation angleto the edge of at least one of the light mixing region and lightemitting region which it directs light into. In one embodiment, thefirst coupling lightguide orientation angle is greater than zero degreesand the border region, along at least one edge or side of the lightemitting device is less than one selected from the group: 20millimeters, 10 millimeters, 5 millimeters, 2 millimeters, 1 millimeter,and 0.5 millimeters. In another embodiment, the coupling lightguides areoriented at an angle along one side of a light emitting device such thatthe light source may be disposed within the inner region of the edgewithout requiring more than one bend or fold of the coupling lightguides

In a further embodiment, a first portion of the border region betweenthe light emitting region and at least one edge or side of the lightemitting device adjacent the light emitting region has a transmissiongreater than 80% and a haze less than 30%. In a further embodiment, afirst portion of the border region between the light emitting region andat least one edge or side of the light emitting device adjacent thelight emitting region has a transmission greater than 85% and a hazeless than 10%. In another embodiment, the border region between thelight emitting region and at least one edge or side of the lightemitting device adjacent the light emitting region has a transmissiongreater than 85% and a haze less than 10%. In another embodiment, theborder region between the light emitting region and at least three edgesor sides of the light emitting device adjacent the light emitting regionhas a transmission greater than 85% and a haze less than 10%.

Luminance Uniformity of the Backlight, Frontlight, or Light EmittingDevice

In one embodiment, a light emitting device comprises a light source, alight input coupler, and a film-based lightguide wherein the 9-spotspatial luminance uniformity of the light emitting surface of the lightemitting device measured according to VESA Flat Panel DisplayMeasurements Standard version 2.0, Jun. 1, 2001 is greater than oneselected from the group: 60%, 70%, 80%, 90%, and 95%. In anotherembodiment, a display comprises a spatial light modulator and a lightemitting device comprising a light source, a light input coupler, and afilm-based lightguide wherein the 9-spot spatial luminance uniformity ofthe light reaching the spatial light modulator (measured by disposing awhite reflectance standard surface such as Spectralon by Labsphere Inc.in the location where the spatial light modulator would be located toreceive light from the lightguide and measuring the light reflectingfrom the standard surface in 9-spots according to VESA Flat PanelDisplay Measurements Standard version 2.0, Jun. 1, 2001) is greater thanone selected from the group: 60%, 70%, 80%, 90%, and 95%. In anotherembodiment, a display comprises a spatial light modulator and a lightemitting device comprising a light source, a light input coupler, and afilm-based lightguide wherein the 9-spot spatial luminance uniformity ofthe display measured according to VESA Flat Panel Display MeasurementsStandard version 2.0, Jun. 1, 2001) is greater than one selected fromthe group: 60%, 70%, 80%, 90%, and 95%.

Color Uniformity of the of the Backlight, Frontlight, or Light EmittingDevice

In one embodiment, a light emitting device comprises a light source, alight input coupler, and a film-based lightguide wherein the 9-spotsampled spatial color non-uniformity, Δu′v′, of the light emittingsurface of the light emitting device measured on the 1976 u′, v′ UniformChromaticity Scale as described in VESA Flat Panel Display MeasurementsStandard version 2.0, Jun. 1, 2001 (Appendix 201, page 249) is less thanone selected from the group: 0.2, 0.1, 0.05, 0.01, and 0.004 whenmeasured using a spectrometer based spot color meter. In anotherembodiment, a display comprises a spatial light modulator and a lightemitting device comprising a light source, a light input coupler, and afilm-based lightguide wherein the 9-spot sampled spatial colornon-uniformity, Δu′v′, of the of the light reaching the spatial lightmodulator (measured by disposing a white reflectance standard surfacesuch as Spectralon in the location where the spatial light modulatorwould be located to receive light from the lightguide and measuring thecolor of the standard surface on the 1976 u′, v′ Uniform ChromaticityScale as described in VESA Flat Panel Display Measurements Standardversion 2.0, Jun. 1, 2001 (Appendix 201, page 249) is less than oneselected from the group: 0.2, 0.1, 0.05, 0.01, and 0.004 when measuredusing a spectrometer based spot color meter. In another embodiment, adisplay comprises a spatial light modulator and a light emitting devicecomprising a light source, a light input coupler, and a film-basedlightguide wherein the 9-spot sampled spatial color non-uniformity,Δu′v′, of the display measured on the 1976 u′, v′ Uniform ChromaticityScale as described in VESA Flat Panel Display Measurements Standardversion 2.0, Jun. 1, 2001 (Appendix 201, page 249) is less than oneselected from the group: 0.2, 0.1, 0.05, 0.01, and 0.004 when measuredusing a spectrometer based spot color meter.

Angular Profile of Light Emitting from the Light Emitting Device

In one embodiment, the light emitting from at least one surface of thelight emitting device has an angular full-width at half-maximumintensity (FWHM) less than one selected from the group: 120 degrees, 100degrees, 80 degrees, 60 degrees, 40 degrees, 20 degrees and 10 degrees.In another embodiment, the light emitting from at least one surface ofthe light emitting device has at least one angular peak of intensitywithin at least one angular range selected from the group: 0-10 degrees,20-30 degrees, 30-40 degrees, 40-50 degrees, 60-70 degrees, 70-80degrees, 80-90 degrees, 40-60 degrees, 30-60 degrees, and 0-80 degreesfrom the normal to the light emitting surface. In another embodiment,the light emitting from at least one surface of the light emittingdevice has two peaks within one or more of the aforementioned angularranges and the light output resembles a “bat-wing” type profile known inthe lighting industry to provide uniform illuminance over apredetermined angular range. In another embodiment, the light emittingdevice emits light from two opposing surfaces within one or more of theaforementioned angular ranges and the light emitting device is oneselected from the group: a backlight illuminating two displays on eitherside of the backlight, a light fixture providing up-lighting anddown-lighting, a frontlight illuminating a display and having lightoutput on the viewing side of the frontlight that has not reflected fromthe modulating components of the reflective spatial light modulator witha peak angle of luminance greater than 40 degrees, 50 degrees, or 60degrees. In another embodiment, the optical axis of the light emittingdevice is within an angular range selected from the group: 0-20, 20-40,40-60, 60-80, 80-100, 100-120, 120-140, 140-160, 160-180, 35-145,45-135, 55-125, 65-115, 75-105, and 85-95 degrees from the normal to alight emitting surface. In further embodiment, the shape of thelightguide is substantially tubular and light substantially propagatesthrough the tube in a direction parallel to the longer (length)dimension of the tube and the light exits the tube wherein at least 70%of the light output flux is contained within an angular range of 35degrees to 145 degrees from the light emitting surface. In a furtherembodiment, the light emitting device emits light from a first surfaceand a second surface opposite the first surface wherein the light fluxexiting the first and second surfaces, respectively, is chosen from thegroup of 5-15% and 85-95%, 15-25% and 75-85%, 25-35% and 65-75%, 35-45%and 65-75%, 45-55% and 45-55%. In another embodiment, the first lightemitting surface emits light in a substantially downward direction andthe second light emitting surface emits light substantially in an upwarddirection. In another embodiment, the first light emitting surface emitslight in a substantially upward direction and the second light emittingsurface emits light substantially in a downward direction.

Optical Redundancy

In one embodiment, the light emitting device comprises couplinglightguides which provide a system for optical redundancy. Opticalredundancy provides for the ability for the device to function atacceptable illuminance uniformity, luminance uniformity, or coloruniformity levels through multiple optical paths from different lightsources that overlap in at least one region. The optical redundancy maybe achieved through stacking lightguides, coupling light from more thanone light source into a light input coupler, or disposing light inputcouplers for the same lightguide film on a plurality of sides of thelightguide (such as on opposite sides of the lightguide). More than onemethod of achieving optical redundancy may be employed, for example, bystacking two or more lightguides that each comprises light inputcouplers that are each disposed to receive light from a plurality oflight sources.

Optical redundancy may be used to increase the spatial or angularuniformity (luminance, illuminance, or color), provide a combination ofangular or spatial light output profiles (low angular output from onelightguide and high angular output from a second lightguide, forexample), provide increased luminance levels, provide a backup lightemitting region when component failure causes light from the firstlightguide to fall below specification (such as color uniformity,luminance uniformity, or luminance) in the overlapping region, increasethe color gamut (combining light output from white and red LEDs forexample), or provide color mixing (combining the output from red, green,and blue LEDs for example).

In one embodiment, optical redundancy is used to maintain or reduce theunwanted effects of light source failure or component failure (such asLED driver or a solder joint failure). For example, two lightguides mayeach be coupled to a separate light input coupler with separate lightsources and the lightguides may be stacked in a light output directionand each independently designed with light extraction features toprovide uniform output in a light emitting region. If the LED fails inthe first light input coupler, the second light input coupler may stilloperate and provide uniform light output. Similarly, if the color of thefirst LED within the first light input coupler changes due totemperature or degradation, the effects (color changes such asoff-white) will be less due to the optical redundancy of a stackedsystem.

In another embodiment, the light output from two or more light sourcesare coupled into the light input coupler of a light emitting devicecomprising optical redundancy and the optical redundancy reduces thecolor or luminance binning requirements of the LEDs. In this embodiment,optical redundancy provides for the mixing of light from a plurality oflight sources within a region (such as within the coupling lightguides)such that the color from each source is averaged spatially with eachcoupling lightguide receiving light from each light source and directingit into the lightguide or light mixing region.

In another embodiment, a light emitting device comprises at least onecoupling lightguide disposed to receive light from at least two lightsources wherein the light from the at least two light sources is mixedwithin a first region of the at least one coupling lightguide and thefirst region is contained within a distance from the light emittingregion of the light emitting device less than one selected from thegroup: 100%, 70%, 50%, 40%, 30%, 20%, 10%, and 5% of the largestdimension of the light emitting device output surface or light emittingregion.

In a further embodiment, a light emitting device comprising a pluralityof light sources comprises optical redundancy and the device may bedimmed by adjusting the light output of one or more LEDs while leavingthe output driving pattern of one or more LEDs substantially constant.For example, a light emitting device comprising a first string of LEDsL1, L2, and L3 connected in an electrical series and optically couplinglight into light input couplers LIC1, LIC2, and LIC3, respectively, andfurther comprising a second string of LEDs L4, L5, and L6 connected inan electrical series and optically coupling light into light inputcouplers LIC1, LIC2, and LIC3, respectively, can be uniformly dimmed(dimmed while maintaining spatial luminance uniformity of the lightemitting surface, for example) from, for example 50% to 100% outputluminance, by adjusting the current to the second string of LEDs.Similarly, the color of the light output can be uniformly adjusted byincreasing or decreasing the electrical current to the second stringwhen the color of the light output of the second string is differentthan the color output of the first string. Similarly, three or morestrings may be controlled independently to provide optical redundancy oruniform adjustment of the luminance or color. Three or more groups withdifferent colors (red, green, and blue, for example) may be adjustedindependently to vary the output color while providing spatial coloruniformity.

Stacked Lightguides

In one embodiment, a light emitting device comprises at least one filmlightguide or lightguide region disposed to receive and transmit lightfrom a second film lightguide or lightguide region such that the lightfrom the second lightguide improves the luminance uniformity, improvesthe illuminance uniformity, improves the color uniformity, increases theluminance of the light emitting region, or provides a back-up lightemitting region when component failure causes light from the firstlightguide to fall below specification (such as color uniformity,luminance uniformity, or luminance) in the overlapping region.

Plurality of Light Sources Coupling into Light Input Coupler

In another embodiment, a plurality of light sources are disposed tocouple light into a light input coupler such that a portion of the lightfrom the plurality of light sources is coupled into at least onecoupling lightguide such that the light output is combined. By combiningthe light output from a plurality of light sources within the couplinglightguides, the light is “mixed” within the coupling lightguides andthe output is more uniform in color, luminance, or both. For example,two white LEDs disposed adjacent a light input surface of a collectionof coupling lightguides within a light input coupler can havesubstantially the same spatial luminance or color uniformity in thelight emitting region if one of the light sources fails. In anotherembodiment, light sources emitting light of two different colors aredisposed to couple light into the same light input coupler. The lightinput coupler may provide the mixing within the coupling lightguides,and furthermore, the coupling lightguides provide optical redundancy incase one light source fails. The optical redundancy can improve thecolor uniformity when light sources of two or more colors are coupledinto the same light input coupler. For example, three white LEDs, eachwith different color temperatures, may be coupled into the same lightinput coupler and if one of the light LEDs fails, then the light outputfrom the other two LEDs is still mixed and provides more uniformity thansingle LEDs with different color outputs coupled into two adjacent lightinput couplers. In one embodiment, a light source comprises at least oneselected from the group: 3, 5, 10, 15, 20, 25 and 30 LED chips disposedin an array or arrangement to couple light into a single light inputcoupler. In one embodiment, a light source comprises at least oneselected from the group: 3, 5, 10, 15, 20, 25 and 30 LED chips disposedin an array or arrangement to couple light into more than one lightinput coupler. In a further embodiment a light source disposed to couplelight into a light input coupler comprises a plurality of LED chips witha light emitting surface area with a light emitting dimension less thanone selected from the group: 0.25 millimeters, 0.3 millimeters, 0.5millimeters, 0.7 millimeters, 1 millimeter, 1.25 millimeters, 1.5millimeters, 2 millimeters and 3 millimeters.

Light Input Couplers on Different Sides of the Lightguide

In another embodiment, a plurality of light input couplers are disposedon two or more edge regions of a lightguide wherein the optical axes ofthe light exiting the coupling lightguides are oriented at an anglegreater than 0 degrees to each other. In a further embodiment, the lightinput couplers are disposed on opposite or adjacent edges or sides ofthe lightguide. In one embodiment, a light emitting device comprises aplurality of light input couplers disposed on two or more edge regionsof a lightguide and the luminance or color uniformity of the lightemitting region is substantially the same when the light output of thefirst light input coupler is increased or decreased relative to thelight output of the second light input coupler. In one embodiment, thelight extraction features are disposed within the light emitting regionsuch that the spatial luminance uniformity is greater than 70% whenreceiving light from only the first light input coupler and receivinglight from the first and second light input couplers. In anotherembodiment, the light extraction features are disposed within the lightemitting region such that the 9-spot spatial color non-uniformity isless than 0.01 when receiving light from only the first light inputcoupler and receiving light from the first and second light inputcouplers.

Other Applications of the Light Emitting Device

Since the present invention enables inexpensive coupling intothin-films, there are many general illumination and backlightingapplications. The first example is general home and office lightingusing roll-out films on walls or ceiling. Beyond that, the film can bendto shape to non-planar shapes for general illumination. Additionally, itcan be used as the backlight or frontlight in the many thin displaysthat have been or are being developed. For example, LCD and E-inkthin-film displays may be improved using a thin back-lighting film orthin front-lighting film; Handheld devices with flexible and scrollabledisplays are being developed and they need an efficient, low-cost methodfor getting light into the backlighting film. In one embodiment, thelight emitting device comprises a light input coupler, lightguide, andlight source which provide illumination for translucent objects or filmsuch as stained glass windows or signs or displays such aspoint-of-purchase displays. In one embodiment, the thin film enables thelight extraction features to be printed such that they overallnegligibly scatter light that propagates normal to the face of the film.In this embodiment, when the film is not illuminated, objects can beseen clearly through the film without significant haze. When placedbehind a transparent or partially transparent stained glass window, theoverall assembly allows low-scattering transmission of light through theassembly if desired. Furthermore, the flexibility of the film allows formuch greater positional tolerances and design freedom than traditionalplate lightguide backlights because the film can be bent and adapted tothe various stained glass window shapes, sizes and topologies. In thisembodiment, when not illuminated, the stained glass appears as a regularnon-illuminated stained glass window. When illuminated, the stainedglass window glows.

Additional embodiments include light emitting devices wherein thestained glass window is strictly aesthetic and does not require viewingof objects through it (e.g. cabinet stained glass windows or artdisplays), and the overall see-through clarity of the backlight does notneed to be achieved. In this embodiment, a diffuse or specular reflectorcan be placed behind the film to capture light that illuminates out ofthe film in the direction away from the stained glass window. Diffusingfilms, light redirecting films, reverse prism films, diffuser films(volumetric, surface relief or a combination thereof) may be disposedbetween the lightguide and the object to be illuminated. Other films maybe used such as other optical films known to be suitable to be usedwithin an LCD backlight.

In another embodiment, a light emitting device is used as an overlaywith indicia that can be illuminated. In one embodiment, the lightguideregion has a low degree of visibility in the off-state, and an in theon-state can be clearly seen as illuminated indicia. For example, thelightguide region may be printed with light scattering dots toilluminate and display indicia such as “Warning,” “Exit,” “Sale,” “EnemyAircraft Detected,” “Open,” “Closed,” “Merry Christmas,” etc. Thelightguide region may be disposed on the viewing side of a display (suchas LCD, Plasma, Projection Screen, etc.) or it may be placed on a storeor home window, on a table surface, a road sign, on a vehicle orair/water/land craft exterior or window, over or inside a transparent,translucent, or opaque object, on a door, stairs, in a hallway, within adoormat, etc. The indicia may also be icons, logos, images, or otherrepresentations such as a cartoon-like drawing of Santa Claus, a brandlogo such as the Nike Swoosh, a photo of a beach scene, a dithered photoof the face of a person, etc. The indicia may be full-color, monochromeor comprise mixtures of colored and monochrome regions and may belayered or employ phosphors, dyes, inks or pigments to achieve colors.

By using a lightguide film which is substantially not visible in theoff-state, the display, sign, or light emitting device can be employedin more places without substantially interfering with appearance of theobject on which it is disposed. In another embodiment, the lightemitting device provides illumination of a space wherein the regionwhich emits light in the on-state is not readily discernible in theoff-state. This, for example, can provide thin light fixtures orillumination devices that are substantially only visible in theon-state. For example, vehicle tail lights, seasonal window filmdisplays, ceiling mounted light fixtures, lamps, closed signs, roadhazard signs, danger/warning signs, etc. may be substantially invisiblein the off-state. In some situations, this enables the signs to beposted and only turned on when needed and can reduce delays incurred dueto the installation time required. In another embodiment, the lightemitting device is a light fixture which appears to be the color of thebackground surface upon which it is place upon in the off-state. Inanother embodiment, the light emitting area of the light fixture issubstantially black or light absorbing in the off-state. Such displaysare useful in submarines or other aircraft under NVIS illuminationconditions.

The light emitting device of one embodiment can be used for backlightingor frontlighting purposes in passive displays, e.g., as a backlight orfrontlight for an illuminated advertising poster, as well as for active(changing) displays such as LCD displays. Suitable displays include, butare not limited to, mobile phone displays, mobile devices, aircraftdisplay, watercraft displays, televisions, monitors, laptops, watches(including one where the band comprises a flexible lightguide which iscapable of illumination or “lighting up” in a predetermined pattern byan LED within the watch or watch band), signs, advertising displays,window signs, transparent displays, automobile displays, electronicdevice displays, and other devices where LCD displays are known to beused.

Some applications generally require compact, low-cost white-lightillumination of consistent brightness and color across the illuminatedarea. It is cost-effective and energy-efficient to mix the light fromred, blue, and green LEDs for this purpose, but color mixing is oftenproblematic. In one embodiment, light from red, blue, and green lightsources is directed into each stack of coupling lightguides/input areasand is sufficiently mixed that it appears as white light when it exitsthe lightguide region of the lightguide. The light sources can begeometrically situated, and adjusted in intensity, to better provideuniform intensities and colors across the lightguide region. A similararrangement can be attained by providing stacked sheets (morespecifically stacked sheet bodies or lightguides) wherein the colors inthe sheets combine to provide white light. Since some displays areprovided on flexible substrates—for example, “E-ink” thin-film displayson printed pages—the sheets provide a means for allowing backlightingwhile maintaining the flexibility of the display's media.

In some embodiments, the light emitting device is a novel LCDbacklighting solution, which includes mixing multiple colors of LEDsinto a single lightguide. In one embodiment, the length and geometry ofthe strips uniformly mixes light into the lightguide region of the filmlightguide without a significant are of light mixing region locatedaround the edge. The enhanced uniformity of the colors can be used for astatic display or a color-sequential LCD and BLU system. One method fora color-sequential system is based on pulsing between red, green, andblue backlight color while synced to the LCD screen pulsing. Moreover, alayered version of red-, green- and blue-lighted films that combine tomake white light is presented. A pixel-based display region can havemultiple pixels that are designated to be red, green or blue. Behind itare three separate film lightguides that each have a separate color oflight coupled to them. Each of the lightguides has light extractionfeatures that match up with the corresponding color of the pixel-baseddisplay. For example, red light is coupled into coupling lightguide andthen into the lightguide or lightguide region and is extracted from thefeature into the red pixel. The film lightguides are considerablythinner than the width of the pixels so that geometrically a highpercentage of the light from a given color goes into its correspondingset of pixels. Ideally, no color filter needs to be used within thepixels, but in case there is cross-talk between pixels, they should beused.

It is also notable that the invention has utility when operated “inreverse”—that is, the light-emitting face(s) of a sheet could be used asa light collector, with the sheet collecting light and transmitting itthrough the coupling lightguides to a photosensitive element. As anexample, sheets in accordance with the invention could collect incominglight and internally reflect it to direct it to a photovoltaic devicefor solar energy collection purposes. Such an arrangement can also beuseful for environmental monitoring sensing purposes, in that the sheetcan detect and collect light across a broad area, and the detector(s) atthe coupling lightguides will then provide a measurement representativeof the entire area. A sheet could perform light collection of thisnature in addition to light emission. For example, in lightingapplications, a sheet might monitor ambient light, and then might beactivated to emit light once twilight or darkness is detected. Usefully,since it is 15 known that LEDs can also be “run in reverse”—that is,they can provide output current/voltage when exposed to light—if LEDsare used as an illumination source when a sheet is used for lightemission, they can also be used as detectors when a sheet is used forlight collection. In one embodiment, the lightguide captures a portionof incident light and directs it to a detector wherein the detector isdesigned to detect a specific wavelength (such as by including abandpass filter, narrowband filter or a diode with a specific bandgapused in reverse). These light detection devices have the advantages ofcollecting a percentage of light over a large area and detecting lightof a specific wavelength is directed toward the film while thefilm/sheet/lightguide/device remains substantially transparent. Thesecan be useful in military operations where one is interested indetecting lasers or light sources (such as used in sighting devices,aiming devices, laser-based weapons, LIDAR or laser based rangingdevices, target designation, target ranging, laser countermeasuredetection, directed energy weapon detection, eye-targeted or dazzlerlaser detection) or infra-red illuminators (that might be used withnight vision goggles).

In another embodiment, a light emitting device comprises a light source,light input coupler, and film-based lightguide wherein the lightemitting device is one selected from the group: can light, trofferlight, cove light, torch lamp, floor lamp, chandelier, surface mountedlight, pendant light, sconce, track light, under-cabinet light,emergency light, wall-socket light, exit light, high bay light, low baylight, strip light, garden light, landscape light, building light,outdoor light, street light, pathway light, bollard light, yard light,accent light, background light, black light, flood light, safelight,safety lamp, searchlight, security light, step light, strobe light,follow-spot light, or wall-washer light.

In another embodiment, a light emitting device comprises a light source,light input coupler, and film-based lightguide wherein the lightemitting device is one selected from the group: building mounted sign,freestanding sign, interior sign, wall sign, fascia sign, awning sign,projecting sign, sign band, roof sign, parapet sign, window sign, canopysign, pylon sign, joint tenant sign, monument sign, pole sign, high-risepole sign, directional sign, electronic message center sign, video sign,electronic sign, billboard, electronic billboard, interior directionalsign, interior directory sign, interior regulatory sign, interior mallsign, and interior point-of-purchase sign.

The sheets are also highly useful for use in illuminated signs,graphics, and other displays. For example, the film may be placed onwalls or windows without significantly changing the wall or windowappearance. However, when the sign is illuminated, the image etched intothe film lightguide would become visible. The present invention couldalso be useful for coupling light into the films that sit in front ofsome grocery store freezers as insulation. Lighting applications wherethere is limited space, such as in the ice at hockey rinks may alsorequire plastic film lighting. Since a sheet can be installed on a wallor window without significantly changing its appearance, with thelight-emitting area(s) becoming visible when the light source(s) areactivated, the invention allows displays to be located at areas wheretypical displays would be aesthetically unacceptable (e.g., on windows).The sheets may also be used in situations where space considerations areparamount, e.g., when lighting is desired within the ice of skatingrinks (as discussed in U.S. Pat. No. 7,237,396, which also describesother features and applications that could be utilized with theinvention). The flexibility of the sheets allows them to be used in lieuof the curtains sometimes used for climate containment, e.g., in thefilm curtains that are sometimes used at the fronts of grocery storefreezers to better maintain their internal temperatures. The flexibilityof the sheets also allows their use in displays that move, e.g., inlight emitting flags that may move in the breeze.

Method of Manufacturing Light Input/Output Coupler

In one embodiment, the lightguide and light input or output coupler areformed from a light transmitting film by creating segments of the filmcorresponding to the coupling lightguides and translating and bendingthe segments such that a plurality of segments overlap. In a furtherembodiment, the input surfaces of the coupling lightguides are arrangedto create a collective light input surface by translation of thecoupling lightguides to create at least one bend or fold.

In another embodiment, a method of manufacturing a lightguide and lightinput coupler comprising a light transmitting film with a lightguideregion continuously coupled to each coupling lightguide in an array ofcoupling lightguides, said array of coupling lightguides comprising afirst linear fold region and a second linear fold region, comprises thesteps of (a) increasing the distance between the first linear foldregion and the second linear fold region of the array of couplinglightguides in a direction perpendicular to the light transmitting filmsurface at the first linear fold region; (b) decreasing the distancebetween the first linear fold region and the second linear fold regionof the array of coupling lightguides in a direction substantiallyperpendicular to the first linear fold region and parallel to the lighttransmitting film surface at the first linear fold region; (c)increasing the distance between the first linear fold region and thesecond linear fold region of the array of coupling lightguides in adirection substantially parallel to the first linear fold region andparallel to the light transmitting film surface at the first linear foldregion; decreasing the distance between the first linear fold region andthe second linear fold region of the array of coupling lightguides in adirection perpendicular to the light transmitting film surface at thefirst linear fold region; (d) such that the coupling lightguides arebent, disposed substantially one above another, and alignedsubstantially parallel to each other. These steps (a), (b), (c) and (d)do not need to occur in alphabetical order and the linear fold regionsmay be substantially parallel.

In one embodiment, the method of assembly includes translating the firstand second linear fold regions of the array of coupling lightguides(segments) in relative directions such that the coupling lightguides arearranged in an ordered, sequential arrangement and a plurality ofcoupling lightguides comprise a curved bend. The coupling lightguidescan overlap and can be aligned relative to one another to create acollection of coupling lightguides. The first linear fold region of thecollection of coupling may be further bent, curved, or folded, glued,clamped, cut, or otherwise modified to create a light input surfacewherein the surface area is suitable to receive and transmit light froma light source into the coupling lightguides. Linear fold regions areregions of the light transmitting film that comprise a fold after thecoupling lightguides are bent in at least one direction. The linear foldregions have a width that at least comprises at least one bend of acoupling lightguide and may further include the region of the filmphysically, optically, or mechanically coupled to a relative positionmaintaining element. The linear fold regions are substantially co-planarwith the surface of the film within the region and the linear foldregions have a length direction substantially larger than the widthdirection such that the linear fold regions have a direction oforientation in the length direction parallel to the plane of the film.In one embodiment, the array of coupling lightguides are oriented at anangle greater than 0 degrees and less than 90 degrees to the firstlinear fold region.

As used herein, the first linear fold region or the second linear foldregion may be disposed near or include the input or output end of thecoupling lightguides. In embodiments where the device is used to collectlight, the input end may be near the light mixing region, lightguideregion, or lightguide and the output end may be near the light emittingedges of the coupling lightguides such as in the case where the couplinglightguides couple light received from the lightguide or lightguideregion into a light emitting surface which is disposed to direct lightonto a photovoltaic cell. In the embodiments and configurationsdisclosed herein, the first linear fold region or second linear foldregion may be transposed to create further embodiments forconfigurations where the direction of light propagation is substantiallyreversed.

In one embodiment, the array of coupling lightguides have a first linearfolding region and a second linear folding region and the method ofmanufacturing the light input coupler comprises translating steps thatcreate the overlap and bends while substantially maintaining therelative position of the coupling lightguides within the first andsecond linear folding regions. In one embodiment, maintaining therelative position of the coupling lightguides assists with the orderedbending and alignment and can allow the coupling lightguide folding andoverlap without creating a disordered or tangled arrangement of couplinglightguides. This can significantly improve the assembly and alignmentand reduce the volume required, particularly for very thin films orcoupling lightguides and/or very narrow coupling light strip widths.

In one embodiment, the aforementioned steps for a method ofmanufacturing a lightguide and light input coupler comprising a lighttransmitting film with a lightguide region are performed such that atleast at least one of steps (a) and (b) occur substantiallysimultaneously; steps (c) and (d) occur substantially simultaneously;and steps (c) and (d) occur following steps (a) and (b). In anotherembodiment, the aforementioned steps for a method of manufacturing alightguide and light input coupler comprising a light transmitting filmwith a lightguide region are performed such that steps (a), (b), and (c)occur substantially simultaneously. The relative translation firstlinear folding region and the second linear folding region of thecoupling lightguides may be achieved by holding a linear folding regionstationary and translating the other linear folding region. In a furtherembodiment, a relative position maintaining elements disposed at thefirst folding region remains substantially stationary while a secondrelative position maintaining element at the second linear foldingregion is translated. The translation may occur in an arc-like patternwithin one or more planes, or in directions parallel to or at an angleto the x, y, or z axis.

In another embodiment, the aforementioned steps are performed whilesubstantially maintaining the relative position of the of the array ofcoupling lightguides within the first linear fold region relative toeach other in a direction parallel to the first linear fold region andsubstantially maintaining the relative position of the array of couplinglightguides within the second linear fold region relative to each otherin a direction parallel to the first linear fold region.

In a further embodiment, the distance between the first linear foldregion and second linear fold region of the array of couplinglightguides is increased by at least the distance, D, that is the totalwidth, W_(t), of the array of the coupling lightguides in a directionsubstantially parallel to the first linear fold region.

In another embodiment, the array of coupling lightguides comprises anumber, N, of coupling lightguides that have substantially the samewidth, W_(s), in a direction parallel to the first linear fold regionand D=N×W_(s).

Relative Position Maintaining Element

In one embodiment, at least one relative position maintaining elementsubstantially maintains the relative position of the couplinglightguides in the region of the first linear fold region, the secondlinear fold region or both the first and second linear fold regions. Inone embodiment, the relative position maintaining element is disposedadjacent the first linear fold region of the array of couplinglightguides such that the combination of the relative positionmaintaining element with the coupling lightguide provides sufficientstability or rigidity to substantially maintain the relative position ofthe coupling lightguides within the first linear fold region duringtranslational movements of the first linear fold region relative to thesecond linear fold region to create the overlapping collection ofcoupling lightguides and the bends in the coupling lightguides. Therelative position maintaining element may be adhered, clamped, disposedin contact, disposed against a linear fold region or disposed between alinear fold region and a lightguide region. The relative positionmaintaining element may be a polymer or metal component that is adheredor held against the surface of the coupling lightguides, light mixingregion, lightguide region or film at least during one of thetranslational steps. In one embodiment, the relative positionmaintaining element is a polymeric strip with planar or saw-tooth-liketeeth adhered to either side of the film near the first linear foldregion, second linear fold region, or both first and second linear foldregions of the coupling lightguides. By using saw-tooth-like teeth, theteeth can promote or facilitate the bends by providing angled guides. Inanother embodiment, the relative position maintaining element is amechanical device with a first clamp and a second clamp that holds thecoupling lightguides in relative position in a direction parallel to theclamps parallel to the first linear fold region and translates theposition of the clamps relative to each other such that the first linearfold region and the second linear fold region are translated withrespect to each other to create overlapping coupling lightguides andbends in the coupling lightguides. In another embodiment, the relativeposition maintaining element maintains the relative position of thecoupling lightguides in the first linear fold region, second linear foldregion, or both the first and second linear fold regions and provides amechanism to exert force upon the end of the coupling lightguides totranslate them in at least one direction.

In another embodiment, the relative position maintaining elementcomprises angular teeth or regions that redistribute the force at thetime of bending at least one coupling lightguide or maintains an evenredistribution of force after at least one coupling lightguide is bentor folded. In another embodiment, the relative position maintainingelement redistributes the force from bending and pulling one or morecoupling lightguides from a corner point to substantially the length ofan angled guide. In another embodiment, the edge of the angled guide isrounded.

In another embodiment, the relative position maintaining elementredistributes the force from bending during the bending operation andprovides the resistance to maintain the force required to maintain a lowprofile (short dimension in the thickness direction) of the couplinglightguides.

In a further embodiment, the relative position maintaining element isalso a thermal transfer element. In one embodiment, the relativeposition maintaining element is an aluminum component with angled guidesor teeth that is thermally coupled to an LED light source.

In a further embodiment, the input ends and output ends of the array ofcoupling lightguides are each disposed in physical contact with relativeposition maintaining elements during the aforementioned steps (a), (b),(c) and (d).

In one embodiment, a relative position maintaining element disposedproximal to the first linear fold region of the array of couplinglightguides has an input cross-sectional edge in a plane parallel to thelight transmitting film that is substantially linear and parallel to thefirst linear fold region, and a relative position maintaining elementdisposed proximal to the second linear fold region of the array ofcoupling lightguides at the second linear fold region of the array ofcoupling lightguides has a cross-sectional edge in a plane parallel tothe light transmitting film at the second linear fold regionsubstantially linear and parallel to the linear fold region.

In another embodiment, the cross-sectional edge of the relative positionmaintaining element disposed proximal to the first linear fold region ofthe array of coupling lightguides remains substantially parallel to thecross-sectional edge of the relative position maintaining elementdisposed proximal to the second linear fold region of the array ofcoupling lightguides during steps (a), (b), (c), and (d).

In a further embodiment, the relative position maintaining elementdisposed proximal to the first linear fold region has a cross-sectionaledge in a plane parallel to the light transmitting film surface disposedproximal to the first linear fold region that comprises a substantiallylinear section oriented at an angle greater than 10 degrees to the firstlinear fold region for at least one coupling lightguide. In a furtherembodiment, the relative position maintaining element has saw-tooth-liketeeth oriented substantially at 45 degrees to a linear fold region ofthe coupling lightguides.

In one embodiment, the cross-sectional edge of the relative positionmaintaining element forms a guiding edge to guide the bend of at leastone coupling lightguide.

In another embodiment, the aforementioned method further comprises thestep of cutting through the overlapping coupling lightguides to providean array of input edges of the coupling lightguides that end insubstantially one plane orthogonal to the light transmitting filmsurface. The coupling lightguides may be formed by cutting the film inlines to form slits in the film. In another embodiment, theaforementioned method of manufacture further comprises forming an arrayof coupling lightguides in a light transmitting film by cuttingsubstantially parallel lines within a light transmitting film. In oneembodiment, the slits are substantially parallel and equally spacedapart. In another embodiment, the slits are not substantially parallelor have non-constant separations.

In another embodiment, the aforementioned method further comprises thestep of holding the overlapping array of coupling lightguides in a fixedrelative position by at least one selected from the group: clamping themtogether, restricting movement by disposing walls or a housing aroundone or more surfaces of the overlapping array of coupling lightguides,and adhering them together or to one or more surfaces.

In another embodiment, a method of manufacturing a lightguide and lightinput coupler comprising a light transmitting film with a lightguideregion continuously coupled to each coupling lightguide in an array ofcoupling lightguides, said array of coupling lightguides comprising afirst linear fold region and a second linear fold region substantiallyparallel to the first fold region, comprises the steps: (a) forming anarray of coupling lightguides physically coupled to a lightguide regionin a light transmitting film by physically separating at least tworegions of a light transmitting film in a first direction; (b)increasing the distance between the first linear fold region and thesecond linear fold region of the array of coupling lightguides in adirection perpendicular to the light transmitting film surface at thefirst linear fold region; (c) decreasing the distance between the firstlinear fold region and the second linear fold region of the array ofcoupling lightguides in a direction substantially perpendicular to thefirst linear fold region and parallel to the light transmitting filmsurface at the first linear fold region; (d) increasing the distancebetween the first linear fold region and the second linear fold regionof the array of coupling lightguides in a direction substantiallyparallel to the first linear fold region and parallel to the lighttransmitting film surface at the first linear fold region; and (e)decreasing the distance between the first linear fold region and thesecond linear fold region of the array of coupling lightguides in adirection perpendicular to the light transmitting film surface at thefirst linear fold region; such that the coupling lightguides are bent,disposed substantially one above another, and aligned substantiallyparallel to each other.

In another embodiment, a method of manufacturing a lightguide and lightinput coupler comprising a light transmitting film with a lightguideregion optically and physically coupled to each coupling lightguide inan array of coupling lightguides, said array of coupling lightguidescomprising a first fold region and a second fold region, comprises thesteps of: (a) translating the first fold region and the second foldregion away from each other in a direction substantially perpendicularto the film surface at the first fold region such that they move towardeach other in a plane parallel to the film surface at the first foldregion and (b) translating the first fold region and the second foldregion away from each other in a direction parallel to the first foldregion such that the first fold region and second fold region movetoward each other in a direction substantially perpendicular to the filmsurface at the first fold region such that the coupling lightguides arebent and disposed substantially one above another.

In one embodiment, stress induced scattering in one or more couplinglightguides induced by bending or folding is reduced by bending orfolding the coupling lightguides at a higher temperature. In anotherembodiment, stress induced scattering in one or more couplinglightguides induced by bending or folding is be reduced after bending orfolding by subjecting one more coupling lightguides or regions ofcoupling lightguides to a temperature higher than one selected from thegroup: the glass transition temperature, the ASTM D1525 Vicat softeningtemperature, the temperature 10 degrees less than the glass transitiontemperature, and the temperature equal to or higher than the melttemperature.

Coupling Lightguides Heated while Bending

In one embodiment, the coupling lightguides are bent or folded whileheated to temperature above 30 degrees Celsius. In one embodiment,coupling lightguides comprising at least one material which results instress induced scattering when bent or folded at a first temperatureless than 30 degrees Celsius are heated to a temperature greater than 30degrees Celsius and bent or folded to create bend or fold regions thatare substantially free of stress induced scattering. A couplinglightguide substantially free of stress induced scattering does notscatter more than 1% of the light propagating within the couplinglightguide out of the lightguide in the bend, fold or stressed regiondue stress induced scattering of light out of the coupling lightguidewhen illuminated with light from a light input coupler. A couplinglightguide substantially free of stress induced scattering does not havesome scattering regions visible by eye in the area of the bend, fold, orstressed region when the coupling lightguide is viewed in transmissionby eye at 5 degrees off-axis to the light incident to the couplinglightguide normal to the surface from a halogen light source collimatedto less than 20 degrees at a distance of 3.048 meters.

In one embodiment, the bending or folding of the coupling lightguidesoccurs at a temperature of at least one selected from the group: greaterthan room temperature, greater than 27 degrees Celsius, greater than 30degrees Celsius, greater than 40 degrees Celsius, greater than 50degrees Celsius, greater than 60 degrees Celsius, greater than the glasstransition temperature of the core material, greater than the glasstransition temperature of the cladding material, greater than the ASTMD1525 Vicat softening temperature of the core material, greater than theASTM D1525 Vicat softening temperature of the cladding material, andgreater than the ASTM D1525 Vicat softening temperature of the couplinglightguide film or film composite.

Coupling Lightguide with Fold Regions

In one embodiment, a lightguide comprises a coupling lightguidecomprising fold regions defined by fold lines and a reflective edge thatsubstantially overlap such that the collection of light input edges forma light input surface. In a further embodiment, one or more fold regionscomprise a first reflective surface edge disposed to redirect a portionof light from a light source input at a light input edge of the filminto an angle less than the critical such that it does not escape thecoupling lightguide at the reflective edge or the lightguide region atan outer edge (such as the edge distal from the light source). Inanother embodiment, one or more fold regions comprise a secondreflective surface edge disposed to redirect a portion of light inputfrom a light input edge of the film into an angle such that it does notescape the coupling lightguide at the reflective edge. In a furtherembodiment, the first and second reflected surface edges substantiallycollimate a portion of the light from the light source. In anotherembodiment, the first and second reflected surface edges have aparabolic shape.

The reflective surface edge may be an edge of the film formed through acutting, stamping or other edge forming technique and the reflectiveproperties may be due to total internal reflection or an applied coating(such as a reflective ink coating or sputter coated aluminum coating).The reflective surface edge may be linear, parabolic, angled, arcuate,faceted or other shape designed to control the angular reflection oflight receive from the light input edge. The first and second reflectivesurface edges may have different shapes or orientations to achievedesired optical functions. The reflective surface edge may serve toredirect light to angles less than the critical angle, collimate light,or redirect light flux to a specific region to improve spatial orangular luminance, color, or light output uniformity.

In one embodiment, the reflective edge is angled, curved, or faceted todirect by total internal reflection a first portion of the light fromthe light source into the lightguide region. In a further embodiment,the reflective edge comprises a reflective coating.

In one embodiment, the fold line is angled or curved such that the foldregions are at least one selected from the group: at an angle to eachother, at an angle to one or more edges of the light input coupler,lightguide region, or light input surface, and at an angle to theoptical axis of a light source, wherein the angle is greater than 0degrees and less than 180 degrees.

One or more regions or edges of the film-based lightguide, such as thereflective edges or the reflective surface edges may be stacked andcoated. For example, more than one lightguide may be stacked to coat thereflective edges using sputter coating, vapor deposition, or othertechniques. Similarly, the reflective surface edges may be folded andcoated with a reflective material. Spacers, protective films or layersor materials may be used to separate the films or edges.

A lightguide with fold regions can reduce or eliminate the need forcutting and folding the coupling lightguides. By forming reflectivesurface edges such as collimating surfaces for light incident from thelight source which are cut from the single film, light can be redirectedsuch that light does not escape out of the lightguide at the angled edge(from the light sources nearest the lightguide region, for example) andthe light from the light source is not coupled out of the lightguide atthe opposite edge (such as light from the LEDs nearest the lightguideincident on the opposite edge of the lightguide region at an angle lessthan the critical angle). In a further embodiment, the shape of thefirst and second reflective surface edges varies from the light sourcenearest the lightguide region or light emitting region toward thefarthest fold region from the lightguide region or light emittingregion. In one embodiment, the light source farthest from the lightguideregion or light emitting region has a second reflective surface edgeformed by the reflective edge and the first reflective surface edge isangled to permit light from the light source to reach the lightguideregion or light emitting region without reflecting from the reflectiveedge. In a further embodiment, the second reflective surface edgesredirect light from the light source incident in a direction away fromthe lightguide region or light emitting region (in the unfolded layout)toward the reflective edge at an angle greater than the critical angleand the first reflective surface edges redirect light from the lightsource incident in a direction toward the lightguide region or lightemitting region toward the reflective edge at an angle greater than thecritical angle or allow light from the light source to directlypropagate toward the lightguide region or light emitting region withoutreflecting from the reflective edge.

In one embodiment, the film-based lightguide with a light input couplercomprising a coupling lightguide with fold regions is formed by foldinga lightguide film along fold lines and overlapping the fold regions at afirst light input edge. In one embodiment, the film-based lightguide isfolded prior to cutting. By folding prior to cutting, the edges of theinternal layers may have improved surface qualities when mechanicallycutting, for example. In a further embodiment, the film-based lightguideis cut prior to folding. By cutting prior to folding, multiplelightguide films may be stacked together to reduce the number of cutsneeded. Additionally, by cutting prior to folding, the first and secondreflective surfaces may have different individual shapes and thereflective edge may be angled or curved.

In a further embodiment, multiple film lightguides are stacked ordisposed one above another in the light input coupler region and thefold regions (or plurality of coupling lightguides) are interwoven oralternating. For example, two film-based lightguides may be stack uponeach other and the fold regions may be simultaneously folded in bothlightguides by a mechanical film folder (such as folding machines usedin the paper industry). This can reduce the number of folding steps, andallow for multiple lightguides to be illuminated by a single light inputcoupler or light source. Interleaving the lightguides can also increasethe uniformity since the light extraction features (location, size,depth, etc.) within each lightguide may be different and independentlycontrolled. Additionally, multiple lightguides wherein the lightguideregion or light emitting regions do not overlap or only partiallyoverlap may be illuminated by a single light input coupler. For example,by folding two lightguides together, the display and backlit keypad in aphone, the display and backlit keyboard in a computer, or the frontlightand keypad in a portable device such as an electronic book may beilluminated by the same light source or light source package.

In a further embodiment, two separate light emitting regions within asingle lightguide film are illuminated by a folded light input coupler(or light input coupler comprising a plurality of coupling lightguides).

The fold regions may be folded to a similar radius of curvature to thecoupling lightguide or strips used in a light input coupler comprising aplurality of coupling lightguides. In another embodiment, the lightguideis held in two or more regions and a plurality of wires are broughttoward each other wherein the wires contact the film near the fold linesin an alternating format and form the bends in the film. The input edgesof the fold regions or regions of the fold regions may then be held orbonded together such that the wires can be removed and the folds remain.In one embodiment, the folds along the fold lines are not “creases” inthat they do not form visible lines or creases when the film isunfolded. In another embodiment, teeth or plates moving in directionstoward each other press alternating fold lines in opposite directionsand create the “zigzag”, accordion-like, or bellow-like folds in thefilm. A housing or fold maintaining element such as a holding device forholding a plurality of coupling lightguides may be used to holdtogether, house, or protect the coupling lightguide formed from aplurality of fold regions. Similarly to the housing or holding devicefor a plurality of coupling lightguides, the housing may comprise anoptically coupled window, refractive lenses or other features, elementsor properties used in the housing, folder, or holding device for aplurality of coupling lightguides. In a further embodiment, the housing,folder, or holding device comprises alternating rigid elements on twoopposing parts such that when the elements are brought together, a filmdisposed between the elements is folded in a bellow-like manner creatingfold regions within a coupling lightguide.

Packaging

In one embodiment, a kit suitable for providing illumination comprises alight source, a light input coupler, and a lightguide.

Roll-Up or Retractable Lightguide

In one embodiment, the flexible light emitting device can be rolled upinto a tube of a diameter less than one selected from the group: 152.4mm, 76.2 mm, 50.8 mm, and 25.4 mm. In another embodiment, the flexiblelight emitting device comprises a spring or elastic-based take-upmechanism which can draw a portion of the lightguide, the light emittingregion, or the lightguide region inside the housing. For example, thelight emitting region of the film can be retracted into a cylindricaltube when a button on the device is pressed to provide secure, protectedstorage.

Lamination or Use with Other Films

In one embodiment, at least one selected from the group: lightguide,light transmitting film, light emitting device housing, thermal transferelement, and component of the light emitting device is laminated to ordisposed adjacent to at least one selected from the group: reflectionfilm, prismatic film reflective polarizer, low refractive index film,pressure sensitive adhesive, air gaps, light absorbing films, anti-glarecoatings, anti-reflection coatings, protective film, barrier film andlow tack adhesive film.

Film Production

In one embodiment, the film or lightguide is one selected from thegroup: extruded film, co-extruded film, cast film, solvent cast film, UVcast film, pressed film, injection molded film, knife coated film, spincoated film and coated film. In one embodiment, one or two claddinglayers are co-extruded on one or both sides of a lightguide region. Inanother embodiment, tie layers, adhesion promotion layers, materials orsurface modifications are disposed on a surface of or between thecladding layer and the lightguide layer.

In another embodiment, at least one selected from the group: lightguidelayer, light transmitting film, cladding region, adhesive region,adhesion promotion region, or scratch resistant layer is coated onto oneor more surfaces of the film or lightguide.

In another embodiment, the lightguide or cladding region is coated onto,extruded onto or otherwise disposed onto a carrier film. In oneembodiment, the carrier film permits at least one of easily handling,fewer static problems, the ability to use traditional paper or packagingfolding equipment, surface protection (scratches, dust, creases, etc.),assisting in obtaining flat edges of the lightguide during the cuttingoperation, UV absorption, transportation protection, and the use ofwinding and film equipment with a wider range of tension and flatness oralignment adjustments. In one embodiment, the carrier film is removedbefore coating the film, before bending the coupling lightguide, afterfolding the coupling lightguides, before adding light extractionfeatures, after adding light extraction features, before printing, afterprinting, before or after converting processes (further lamination,bonding, die cutting, hole punching, packaging, etc.), just beforeinstallation, after installation (when the carrier film is the outersurface), and during the removal process of the lightguide frominstallation.

In another embodiment, the carrier film is slit or removed across aregion of the coupling lightguides. In this embodiment, the couplinglightguides can be bent or folded to a smaller radius of curvature afterthe carrier film is removed from the linear fold region.

Separate Coupling Lightguides

In another embodiment, the coupling lightguides are discontinuous withthe lightguide and are subsequently optically coupled to the lightguide.In one embodiment, the coupling lightguides are one selected from thegroup: extruded onto the lightguide, optically coupled to the lightguideusing an adhesive, optically coupled to the lightguide by injectionmolding a light transmitting material that bonds or remains in contactwith the coupling lightguides and lightguide, thermally bonded to thelightguide, solvent bonded to the lightguide, laser welded to thelightguide, sonic welded to the lightguide, chemically bonded to thelightguide, and otherwise bonded, and adhered or disposed in opticalcontact with the lightguide. In one embodiment, the thickness of thecoupling lightguides is one selected from the group: less than 80%, lessthan 70%, less than 50%, less than 40%, less than 20%, less than 10% ofthe thickness of the lightguide.

Glass Laminate

In another embodiment, the lightguide is disposed within or on one sideof a glass laminate. In another embodiment, the lightguide is disposedwithin a safety glass laminate. In a further embodiment, at least oneselected from the group: lightguide, cladding, and adhesive layercomprises polyvinyl butyrate.

Patterned Lightguides

In another embodiment, at least one selected from the group: lightguideor coupling lightguides is a coated region disposed on a cladding,carrier film, substrate or other material. By using a coated pattern forthe lightguide, different pathways for the light can be achieved forlight directed into the coupling lightguides or lightguide. In oneembodiment, the lightguide region comprises lightguide regions whichdirect light to separate light emitting regions wherein the neighboringlightguide regions with light extracting features emit light of adifferent color. In another embodiment, a lightguide pattern is disposedon a cladding layer, carrier film, or other layer which comprisesregions disposed to emit light of two or more colors from two or morelight sources coupled into input couplers with coupling lightguidesdisposed to direct light from the light source to the correspondingpatterned (or trace) lightguide. For example, a red LED may be disposedto couple light into a light input coupler with coupling lightguides(which may be film-based or coating based or the same material used forthe pattern lightguide coating) to a lightguide pattern wherein thelight extraction features emit light in a pattern to provide color in apixilated color display. In one embodiment, the lightguide pattern orthe light extracting region patterns within the lightguide patterncomprises one or more selected from the group: curved sections, bendstraight sections, shapes, and other regular and irregular patterns. Thecoupling lightguides may be comprised of the same material as thepatterned lightguides or they may be a different material.

Light Extraction Features

In one embodiment, the light extraction features are disposed on orwithin a film, lightguide region or cladding region by embossing oremploying a “knurl roll” to imprint surface features on a surface. Inanother embodiment, the light extraction features are created byradiation (such as UV exposure) curing a polymer while it is in contactwith a drum, roll, mold or other surface with surface features disposedthereon. In another embodiment, light extraction features are formed inregions where the cladding or low refractive index material or othermaterial on or within the lightguide is removed or formed as a gap. Inanother embodiment, the lightguide region comprises a light reflectingregion wherein light extraction features are formed where the lightreflecting region is removed. Light extraction may comprise or bemodified (such as the percent of light reaching the region that isextracted or direction profile of the extracted light) by addingscattering, diffusion, or other surface or volumetric prismatic,refracting, diffracting, reflecting, or scattering elements within oradjacent the light extraction features or regions where the cladding orother layer has been removed.

In one embodiment, the light extraction features are volumetric lightredirecting features that refract, diffract, scatter, reflect, totallyinternally reflect, diffuse, or otherwise redirect light. The volumetricfeatures may be disposed within the lightguide, lightguide region, core,cladding, or other layer or region during the production of the layer orregion or the features may be disposed on a surface whereupon anothersurface or layer is subsequently disposed.

In one embodiment, the light extraction features comprise an ink ormaterial within a binder comprising least one selected from the group:titanium dioxide, barium sulfate, metal oxides, microspheres or othernon-spherical particles comprising polymers (such as PMMA, polystyrene),rubber, or other inorganic materials. In one embodiment, the ink ormaterial is deposited by one selected from the group: thermal inkjetprinting, piezoelectric inkjet printing, continuous inkjet printing,screen printing (solvent or UV), laser printing, sublimation printing,dye-sublimation printing, UV printing, toner-based printing, LED tonerprinting, solid ink printing, thermal transfer printing, impactprinting, offset printing, rotogravure printing, photogravure printing,offset printing, flexographic printing, hot wax dye transfer printing,pad printing, relief printing, letterpress printing, xerography, solidink printing, foil imaging, foil stamping, hot metal typesetting,in-mold decoration, and in-mold labeling.

In another embodiment, the light extraction features are formed byremoving or altering the surface by one selected from the group:mechanical scribing, laser scribing, laser ablation, surface scratching,stamping, hot stamping, sandblasting, radiation exposure, ionbombardment, solvent exposure, material deposition, etching, solventetching, plasma etching, and chemical etching.

In a further embodiment, the light extraction features are formed byadding material to a surface or region by one selected from the group:UV casting, solvent casting with a mold, injection molding,thermoforming, vacuum forming, vacuum thermoforming, and laminating orotherwise bonding or coupling a film or region comprising surfacerelief, and volumetric features.

In one embodiment, at least one selected from the group: mask, tool,screen, patterned film or component, photo resist, capillary film,stencil, and other patterned material or element is used to facilitatethe transfer of the light extraction feature to the lightguide, film,lightguide region, cladding region or a layer or region disposed on orwithin the lightguide.

In another embodiment, more than one light extraction layer or regioncomprising light extraction features is used and the light extractionlayer or region may be located on one surface, two surfaces, within thevolume, within multiple regions of the volume, or a combination of theaforementioned locations within the film, lightguide, lightguide region,cladding, or a layer or region disposed on or within the lightguide.

In another embodiment, surface or volumetric light extraction featuresare disposed on or within the lightguide or cladding or a region orsurface thereon or between that direct at least one selected from thegroup: 20%, 40%, 60%, and 80% of light incident from within thelightguide to angles within 30 degrees from the normal to the lightemitting surface of the light emitting device or within 30 degrees fromthe normal of a reflecting surface such as a reflective spatial lightmodulator.

Folding and Assembly

In one embodiment, the coupling lightguides are heated to soften thelightguides during the folding or bending step. In another embodiment,the coupling lightguides are folded while they are at a temperatureabove one selected from the group: 50 degrees Celsius, 70 degreesCelsius, 100 degrees Celsius, 150 degrees Celsius, 200 degrees Celsius,and 250 degrees Celsius.

Folder

In one embodiment, the coupling lightguides are folded or bent usingopposing folding mechanisms. In another embodiment, grooves, guides,pins, or other counterparts facilitate the bringing together opposingfolding mechanisms such that the folds or bends in the couplinglightguides are correctly folded. In another embodiment, registrationguides, grooves, pins or other counterparts are disposed on the folderto hold in place or guide one or more coupling lightguides or thelightguide during the folding step. In one embodiment, at least one ofthe lightguide or coupling lightguides comprises a hole and the holdercomprises a registration pin and when the pin is positioned through thehole before and during the folding step, the lightguide or couplinglightguide position relative to the holder is fixed in at least onedirection. Examples of folding coupling lightguides or strips forlightguides are disclosed in International Patent Application numberPCT/US08/79041 entitled “Light coupling into illuminated films.”

In one embodiment, the folding mechanism has an opening disposed toreceive a strip that is not to be folded in the folding step. In oneembodiment, this strip is used to pull the coupling lightguides into afolded position, pull two components of the folding mechanism together,align the folding mechanism components together, or tighten the foldingsuch that the radius of curvature of the coupling lightguides isreduced.

In one embodiment, at least one selected from the group: foldingmechanism, relative position maintaining element, holder, or housing isformed from one selected from the group: sheet metal, foil, film, rigidrubber, polymer material, metal material, composite material, and acombination of the aforementioned materials.

Holder

In one embodiment, a light emitting device comprises a folding mechanismwhich substantially maintains the relative position of the couplinglightguides subsequent to the folding operation. In another embodiment,the folder or housing comprises a cover that is disposed over (such asslides over, folds over, hinges over, clips over, snaps over, etc.) thecoupling lightguides and provides substantial containment of thecoupling lightguides. In a further embodiment, the folding mechanism isremoved after the coupling lightguides have been folded and the holdingmechanism is disposed to hold the relative position of the couplinglightguides. In one embodiment, the holding mechanism is a tube with acircular, rectangular, or other geometric shape cross-sectional profilewhich slides over the coupling lightguides and further comprises a slitwhere the coupling lightguides, light mixing region, or lightguide exitsthe tube. In one embodiment, the tube is one selected from the group:transparent, black, has inner walls with a diffuse luminous reflectancegreater than 70%, and has a gloss less than 50 in a region disposedproximate a coupling lightguide such that the surface area of the innertube in contact with the coupling lightguide remains small.

In a further embodiment, a method of manufacturing a light input couplerand lightguide comprises at least one step selected from the group:holding the coupling lightguide, holding the lightguide, cutting theregions in the film corresponding to the coupling lightguides, andfolding or bending the coupling lightguides wherein the relativeposition maintaining element holds the lightguide or coupling lightguideduring the cutting and the folding or bending step. In anotherembodiment, a method of manufacturing a light input coupler andlightguide comprises cutting the coupling lightguides in a film followedby folding or bending the coupling lightguides wherein the samecomponent holding the coupling lightguides or lightguide in place duringthe cutting also holds the coupling lightguide or lightguide in placeduring the folding or bending.

In another embodiment, the relative position of at least one region ofthe coupling lightguides are substantially maintained by one or moreselected from the group: wrapping a band, wire, string, fiber, line,strap, wrap or similar tie material around the coupling lightguides or aportion of the coupling lightguides, disposing a housing tube, case,wall or plurality of walls or components around a portion of thecoupling lightguides, wrapping a heat-shrinking material around thecoupling lightguides and applying heat, bonding the coupling lightguidesusing adhesives, thermal bonding or other adhesive or bonding techniquesin one or more regions of the coupling lightguides (such as near theinput end, for example), clamping the lightguides, disposing a lowrefractive index epoxy, adhesive, or material around, or between one ormore regions of the coupling lightguides, pressing together couplinglightguides comprising a pressure sensitive adhesive (or UV cured orthermal adhesive) on one or both sides. In one embodiment, the couplinglightguide region of a film comprises a pressure sensitive adhesivewherein after the coupling lightguides are cut into the film with theadhesive, the coupling lightguides are folded on top of one another andpressed together such that the pressure sensitive adhesive holds them inplace. In this embodiment, the pressure sensitive adhesive can have alower refractive index than the film, and operate as cladding layer.

In another embodiment, the folder and/or holder has a plurality ofsurfaces disposed to direct, align, bring the coupling lightguidestogether, direct the coupling lightguides to become parallel, or directthe input surfaces of the coupling lightguides toward a light inputsurface disposed to receive light from an LED when the couplinglightguides are translated in the folder or holder. In one embodiment,the coupling lightguides are guided into a cavity that aligns thecoupling lightguides parallel to each other and disposes the input edgesof the coupling lightguides near an input window. In one embodiment, thewindow is open, comprises a flat outer surface, or comprises an opticalouter surface suitable for receiving light from a light source.

Hold-Down Mechanism

In one embodiment, at least one coupling lightguide comprises at leastone hook region disposed near the input surface end of the couplinglightguide. The hook region allows a guide, alignment mechanism, orpull-down mechanism to maintain at least one selected from the group:the relative position of the ends or regions near the ends of thecoupling lightguides, the relative separations of the couplinglightguides to each other in the thickness direction of the couplinglightguide, the positions of the coupling lightguides relative to thelightguide in the thickness direction of the lightguide, and thepositions of the end regions or the ends of the coupling lightguides inone or more directions in a plane substantially parallel to thelightguide. In one embodiment, the hook region comprises at leastselected from the group: a flange, a barb, a protrusion, a hole, or anaperture region in the coupling lightguide. In one embodiment, thelightguide or a means for manufacturing a film-based lightguidecomprises a hold down mechanism comprising two hook regions comprisingflanges on either side of at least one coupling lightguide wherein theflanges permit a strap, wire or other film or object to be positionedagainst the hook region such that the strap, strip, wire or other filmor object substantially maintains the relative position of the ends ofthe coupling lightguide in at least one direction. In anotherembodiment, the hold down mechanism comprises a physical restrainingmechanism for holding or maintaining the hold down mechanism or the hookregion in at least one direction relative to a temporary or permanentbase or other component such as holder, relative position maintainingelement, housing, thermal transfer element, guide, or tension formingelement. In another embodiment, the lightguide or a means formanufacturing a film-based lightguide comprises a hold down mechanismcomprising a hook region comprising two holes on either side of thecoupling lightguides or near the input end of the coupling lightguides,and the coupling lightguides may be stacked on top of each other and ontop of a base element comprising two pins that align with the holes. Thepins and holes register the ends of the coupling lightguides andsubstantially maintain their relative positions near the input end ofthe coupling lightguides. In another embodiment, one or more couplinglightguides comprise a hook region that can be removed after thehold-down mechanism forces the coupling lightguides together. In anotherembodiment, the hook region may be removed along with a portion of theend of the coupling lightguides. In one embodiment, the hook regions andthe ends of the coupling lightguides are cut, peeled or town off afterthe coupling lightguides have been strapped or physically coupled to abase or other element. After the hook regions and the couplinglightguides are cut from the remainder of the coupling lightguides, thenew ends of the coupling lightguides may form an input surface or asurface suitable to optically couple to one or more optical elementssuch as windows or secondary optics.

In another embodiment, one or more coupling lightguide comprise aremovable hook region comprising an aperture cut from the lightguidethat forms the light input surface for the coupling lightguide afterremoving the hook region. For example, in one embodiment, an array ofcoupling lightguides are cut into a film wherein the end region of thecoupling lightguide near the input edge comprises shoulder-like flangesthat extend past the average width of the coupling lightguides andfurther comprises an aperture cut that extends more than 20% of thewidth of the coupling lightguides. In this embodiment, the lateral edgesof the coupling lightguides and aperture cut can be cut during the sameprocess step and they can both comprises high quality surface edges.When the edge region is removed from the ends of the couplinglightguides using the aperture cut as a separation guide after stackingand aligning using the shoulder-like flanges, the stack of couplinglightguides have a light input surface formed from the collection ofedges formed by the aperture cut. Similarly, pin and hole type hookregions may be used and in one embodiment, the hook region does notextend past the width of the coupling lightguides. For example, holesnear the width ends of the coupling lightguides may be used as hookregions.

In another embodiment, one or more coupling lightguides is physicallycoupled to a hold down mechanism and the hold down mechanism istranslated in a first direction substantially parallel to the axis ofthe coupling lightguides such that the coupling lightguides move closertogether, closer to the lightguide, or closer to the base. For example,in one embodiment, the end region of the coupling lightguides comprisesholes that are aligned onto a pin under low tension. After the couplinglightguides are aligned onto the pins, the pins and the base supportingthe pins is translated in a direction away from the coupling lightguidessuch that the coupling lightguide pull closer toward each other and thebase.

Converting or Secondary Operations on the Film or Light Input Coupler

In one embodiment, at least one selected from the group: couplinglightguides, lightguide, light transmitting film, lightguide region,light emitting region, housing, folder, and holder component is stamped,cut, thermoformed, or painted. In one embodiment, the cutting of thecomponent is performed by one selected from the group: knife, scalpel,heated scalpel, die cutter, water jet cutter, saw, hot wire saw, lasercutter, or other blade or sharp edge. One or more components may bestacked before the cutting operation.

In one embodiment, the component is thermoformed (under a vacuum,ambient pressure, or at another pressure) to create a curved or bentregion. In one embodiment, the film is thermoformed into a curve and thecoupling lightguide strips are subsequently cut from the curved film andfolded in a light input coupler.

In one embodiment, at least one edge selected from the group: couplinglightguide, lightguide, light transmitting film, collection of couplinglightguides, and edge of other layer or material within the lightemitting device is modified to become more planar (closer to opticallyflat), roughened, or formed with a predetermined structure to redirectlight at the surface (such as forming Fresnel refracting features onedges of the input coupling lightguides in a region of the collection ofcoupling lightguides to direct light into the coupling lightguides in adirection closer to a direction parallel to the plane of the couplinglightguides at the input surface (for example, forming a Fresnelcollimating lens on the surface of the collection of couplinglightguides disposed near an LED). In one embodiment, the edgemodification substantially polishes the edge by laser cutting the edge,mechanically polishing the edge, thermally polishing (surface melting,flame polishing, embossing with a flat surface), chemically polishing(caustics, solvents, methylene chloride vapor polishing, etc.).

Reflective Coating or Element

In one embodiment, at least one region of at least one edge selectedfrom the group: coupling lightguide, film, and lightguide comprises asubstantially specularly reflecting coating or element optically coupledto the region or disposed proximal to the edge. In one embodiment, thesubstantially specularly reflecting element or coating can redirectlight a portion of the light exiting the coupling lightguide,lightguide, or film edge back into the coupling lightguide, lightguideor film at an angle that will propagate by TIR within the lightguide. Inone embodiment, the specularly reflective coating is a dispersion oflight reflecting material disposed in an ink or other binder selectedfrom the group: dispersions of aluminum, silver, coated flakes,core-shell particles, glass particles, and silica particles. In anotherembodiment, the dispersion comprises particle sizes selected from one ofthe group of less than 100 microns in average size, less than 50 micronsin average size, less than 10 microns in average size, less than 5microns in average size, less than 1 micron in average size, less than500 nm in average size. In another embodiment, the dispersion comprisessubstantially planar flakes with an average dimension in a directionparallel to the flake surface selected from one of the group of lessthan 100 microns in average size, less than 50 microns in average size,less than 10 microns in average size, less than 5 microns in averagesize, less than 1 micron in average size, less than 500 nm in averagesize. In another embodiment, the coupling lightguides are folded andstacked and a light reflecting coating is applied in regions on theedges of the lightguide. In another embodiment, the light reflectingcoating is applied to the tapered region of the collection of couplinglightguides. In a further embodiment, the blade that cuts through thefilm, coupling lightguide, or lightguide passes through the film duringthe cutting operation and makes contact with a well comprisingreflective ink and the ink is applied to the edge when the blade passesback by the edge of the film. In another embodiment, a multilayerreflection film, such as a specularly reflecting multilayer polymer filmis disposed adjacent to or in optical contact with the couplinglightguides in a region covering at least the region near the edges ofthe coupling lightguides, and the specularly reflecting multilayerpolymer film is formed into substantially a 90 bend forming a reflectedside to the coupling lightguide. The bending or folding of thereflective film may be achieved during the cutting of the lightguide,coupling lightguides, or tapered region of the coupling lightguides. Inthis embodiment, the reflective film may be adhered or otherwisephysically coupled to the film, coupling lightguide, collection ofcoupling lightguides, or lightguide and the fold creates a flatreflective surface near the edge to reflect light back into thelightguide, film, coupling lightguide or collection of couplinglightguides. The folding of the reflective film may be accomplished bybending, pressure applied to the film, pressing the lightguide such thata wall or edge bends the reflective film. The reflective film may bedisposed such that it extends past the edge prior to the fold. Thefolding of the reflective film may be performed on multiple stackededges substantially simultaneously.

The following are more detailed descriptions of various embodimentsillustrated in the Figures.

FIG. 1 is a top view of one embodiment of a light emitting device 100comprising a light input coupler 101 disposed on one side of afilm-based lightguide. The light input coupler 101 comprises couplinglightguides 104 and a light source 102 disposed to direct light into thecoupling lightguides 104 through a light input surface 103 comprisingone or more input edges of the coupling lightguides 104. In oneembodiment, each coupling lightguide 104 includes a coupling lightguideterminating at a bounding edge. Each coupling lightguide is folded suchthat the bounding edges of the coupling lightguides are stacked to formthe light input surface 103. The light emitting device 100 furthercomprises a lightguide region 106 comprising a light mixing region 105,a lightguide 107, and a light emitting region 108. Light from the lightsource 102 exits the light input coupler 101 and enters the lightguideregion 106 of the film. This light spatially mixes with light fromdifferent coupling lightguides 104 within the light mixing region 105 asit propagates through the lightguide 107. In one embodiment, light isemitted from the lightguide 107 in the light emitting region 108 due tolight extraction features (not shown).

FIG. 2 is a perspective view of one embodiment of a light input coupler200 with coupling lightguides 104 folded in the −y direction and stackedin the z direction (direction of the stack). Light from the light source102 is directed into the light input surface 103 comprising input edges204 of the coupling lightguides 104. A portion of the light from thelight source 102 propagating within the coupling lightguides 104 with adirectional component in the +y direction will reflect in the +x and −xdirections from the lateral edges 203 of the coupling lightguides 104and will reflect in the +z and −z directions from the top and bottomsurfaces of the coupling lightguides 104. The light propagating withinthe coupling lightguides is redirected by the folds 201 in the couplinglightguides 104 toward the −x direction.

FIG. 3 is a top view of one embodiment of a light emitting device 300with three light input couplers 101 on one side of the lightguide region106 comprising the light mixing region 105, a lightguide 107, and thelight emitting region 108.

FIG. 4 is a top view of one embodiment of a light emitting device 400with two light input couplers 101 disposed on opposite sides of thelightguide 107. In certain embodiments, one or more input couplers 101may be positioned along one or more corresponding sides of thelightguide 107.

FIG. 5 is a top view of one embodiment of a light emitting device 500with two light input couplers 101 disposed on the same side of thelightguide region 106. The light sources 102 are oriented substantiallywith the light directed toward each other in the +y and −y directions.

FIG. 6 is a cross-sectional side view of one embodiment of a lightemitting device 600 defining a region 604 near a substantially planarlight input surface 603 comprised of planar edges of couplinglightguides 104 disposed to receive light from a light source 102. Thecoupling lightguides comprise core regions 601 and cladding regions 602.A portion of the light from the light source 102 input into the coreregion 601 of the coupling lightguides 104 will totally internallyreflect from the interface between the core region 601 and the claddingregion 602 of the coupling lightguides 104. In the embodiment shown inFIG. 6, a single cladding region 602 is positioned between adjacent coreregions 601. In another embodiment, two or more cladding regions 602 arepositioned between adjacent core regions 601.

FIG. 7 is a cross-sectional side view of one embodiment of a lightemitting device 700 defining a region 704 near a light input surface ofthe light input coupler 101 having one or more planar surface features701 substantially parallel to stack direction (z direction as shown inFIG. 7) of the coupling lightguides 104, one or more refractive surfacefeatures 702, and one or more planar input surfaces 703 and a bevelformed on an opposite surface of the coupling lightguide 104 thattotally internally reflects a portion of incident light into thecoupling lightguide 104 similar to a hybrid refractive-TIR Fresnel lens.

FIG. 8 is a cross-sectional side view of one embodiment of a lightemitting device 800 defining a region 802 near a light input surface ofthe light emitting device 800. The coupling lightguides 104 areoptically coupled to the light source 102 by an optical adhesive 801 orother suitable coupler or coupling material. In this embodiment, lesslight from the light source 102 is lost due to reflection (andabsorption at the light source or in another region) and the positionalalignment of the light source 102 relative to the coupling lightguides104 is easily maintained.

FIG. 9 is a cross-sectional side view of one embodiment of a lightemitting device 900 defining a region 903 near a light input surface ofthe light emitting device 900. In this embodiment, the couplinglightguides 104 are held in place by a sleeve 901 with an outer couplingsurface 902 and the edge surfaces of the coupling lightguides 104 areeffectively planarized by an optical adhesive 801 between the ends ofthe coupling lightguides and the sleeve 901 with the outer surface 902adjacent the light source 102. In this embodiment, the surface finish ofthe cutting of the coupling lightguides is less critical because theouter surface 902 of the sleeve 901 is optically coupled to the edgesusing an optical adhesive 801 which reduces the refraction (andscattering loss) that could otherwise occur at the air-input edgeinterface of the input edge due to imperfect cutting of the edges. Inanother embodiment, an optical gel, a fluid or a non-adhesive opticalmaterial may be used instead of the optical adhesive to effectivelyplanarize the interface at the edges of the coupling lightguides. Incertain embodiments, the difference in the refractive index between theoptical adhesive, the optical gel, the fluid, or the non-adhesiveoptical material and the core region of the coupling lightguides is lessthan one selected from group of 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, and0.01. In one embodiment, the outer surface 902 of the sleeve 901 issubstantially flat and planar.

FIG. 10 is a top view of one embodiment of a light emitting backlight1000 configured to emit red, green, and blue light. The light emittingbacklight 1000 includes a red light input coupler 1001, a green lightinput coupler 1002, and a blue light input coupler 1003 disposed toreceive light from a red light source 1004, a green light source 1005,and a blue light source 1006, respectively. Light from each of the lightinput couplers 1001, 1002, and 1003 is emitted from the light emittingregion 108 due to the light extraction features 1007 which redirect aportion of the light to angles closer to the surface normal within thelightguide region 106 such that the light does not remain within thelightguide 107 and exits the light emitting device 1000 in a lightemitting region 108. The pattern of the light extraction features 1007may vary in one or more of size, space, spacing, pitch, shape, andlocation within the x-y plane or throughout the thickness of thelightguide in the z direction.

FIG. 11 is a cross-sectional side view of one embodiment of a lightemitting device 1100 comprising the light input coupler 101 and thelightguide 107 with a reflective optical element 1101 disposed adjacenta the cladding region 602 and a light source 1102 with an optical axisin the +y direction disposed to direct light into the couplinglightguides 104. Light from the light source 1102 propagates through thecoupling lightguides 104 within the light input coupler 101 and throughthe light mixing region 105 and the light output region 108 within thelightguide region 106. Referring to FIG. 11, a first portion of light1104 reaching the light extraction features 1007 is redirected towardthe reflecting optical element 1101 at an angle less than the criticalangle such that it can escape the lightguide 107, reflect from thereflective optical element 1101, pass back through the lightguide 107,and exit the lightguide 107 through the light emitting surface 1103 ofthe light emitting region 108. A second portion of light 1105 reachingthe light extraction features 1007 is redirected toward the lightemitting surface 1103 at an angle less than the critical angle, escapesthe lightguide 107, and exits the lightguide 107 through the lightemitting surface 1103 of the light emitting region 108.

FIG. 12 is a cross-sectional side view of one embodiment of a lightemitting display 1200 illuminated by a red lightguide 1201, a greenlightguide 1202, and a blue lightguide 1203. The locations of the pixelsof the display panel 1204 with corresponding red pixels 12010, greenpixels 1209, and blue pixels 1208 correspond to light emitting regionsof the lightguide separated by color. In this embodiment, the lightextracting features 1205 within the red lightguide 1201 substantiallycorrespond in the x-y plane to the red pixels 1210 of the display panel1204 driven to display red information. Similarly, the green lightextracting features 1206 within the green lightguide 1202 and the bluelight extracting features 1207 within the blue lightguide 1203substantially correspond in the x-y plane to the green pixels 1209 andthe blue pixels 1208, respectively, of the display panel 1204 driven todisplay corresponding green and blue information. In another embodiment,the display panel 1204 is a spatial light modulator such as a liquidcrystal panel, electrophoretic display, MEMS-based display,ferroelectric liquid crystal panel, or other spatial light modulatingdevice such as known in the display industry. In another embodiment, thedisplay panel 1204 further comprises color filters within the pixelregions to further reduce crosstalk from lightguide illuminationreaching the pixel from neighboring light extracting features. Inanother embodiment, the lightguides are optically coupled to each otherand the reflecting optical element is a specularly reflecting opticalelement. In a further embodiment, the liquid crystal panel is atransparent LCD (such as a vertical alignment type from SamsungElectronics with a transparent cathode) and there is no reflectingoptical element on the opposite side of the lightguides than the displaypanel. In this embodiment, the display and backlight are substantiallytransparent and “see-through” with an ASTM D1003 total luminoustransmittance greater than one selected from the group: 20%, 30%, 40%,and 50%.

FIG. 13 is a cross-sectional side view of one embodiment of a colorsequential display 1300 comprising a color sequential display panel 1301and a red, green, and blue color sequential light emitting backlight1302 comprising a film-based lightguide. In this embodiment, red, green,and blue light from red, green and blue light sources (not shown in FIG.13) is coupled into the lightguide through one or more light inputcouplers (not shown in FIG. 13). The light sources are driven in a colorsequential mode and the pixel regions of the display panel 1301 areswitched accordingly to display the desired color information. In oneembodiment, the display panel 1301 is a spatial light modulator withoutcolor filters. FIG. 14 is a cross-sectional side view of one embodimentof a spatial display 1400 comprising a spatial light modulator 1401 anda film-based backlight 1402 emitting light from light sources ofdifferent colors. In one embodiment, the spatial display is a liquidcrystal display. In another embodiment, the spatial light modulator is aliquid crystal panel. In a further embodiment, the film-based backlightemits light from one selected from the group: red, green, and blue;white and red; red, green, blue, and yellow; red, green, blue, yellow,and cyan; and cyan, yellow, and magenta.

FIG. 15 is a cross-sectional side view of one embodiment of a spatialdisplay 1500 comprising a spatial light modulator 1401 and a film-basedbacklight 1501 emitting white light.

FIG. 16 is a cross-sectional side view of one embodiment of a spatialdisplay 1600 comprising a spatial light modulator 1401 and a backlight1601 comprising a film-based lightguide 107 emitting blue light, UVlight, or a combination of blue and UV light. A portion of this lightpasses through a wavelength converting layer 1602 and is converted tolight of a second color. In one embodiment, the wavelength convertinglayer 1602 is a phosphor film. In another embodiment, the wavelengthconverting layer 1602 is a layer comprising quantum dots. FIG. 17 is across sectional side view of one embodiment of a light emitting display1700 illuminated by a backlight 1710 comprising a plurality oflightguides emitting different colored light in predetermined spatialpatterns. The display panel 1730 is illuminated by a red film-basedlightguide 1702, a green film-based lightguide 1703, and a bluefilm-based lightguide 1704 optically coupled to each other and thedisplay panel 1730 by an optical adhesive 1701 with a refractive indexlower than the refractive index of the lightguide. In one embodiment,the refractive index of the optical adhesive 1701 is less than therefractive index of the lightguides (1702, 1703, and 1704) by oneselected from the group: 0.5, 0.4, 0.3, 0.2, 0.1, 0.05 and 0.01. The redpixels 1721, green pixels 1722, and the blue pixels 1723 of the displaypanel 1730 correspond to the light emitting regions of the lightguidesseparated by color. In this embodiment, the light extracting features1711 within the red lightguide 1702 substantially correspond in the x-yplane to the red pixels 1721 of the display panel 1730 driven to displayred information. Similarly, the green light extracting features 1712within the green lightguide 1703 and the blue light extracting features1713 within the blue lightguide 1704 substantially correspond in the x-yplane to the green pixels 1722 and the blue pixels 1723, respectively,of the display panel 1730 driven to display corresponding green and blueinformation. In one embodiment, the reflective optical element 1101 isspecularly reflecting. In another embodiment, the total thickness of thered, green, and blue lightguides (1702, 1703, 1704) and the opticaladhesive layers 1701 disposed between the red, green, and bluelightguides (1702, 1703, 1704) is less than 100 microns. In anotherembodiment, the red, green, and blue lightguides 1702, 1703, and 1704are formed by co-extruding the lightguide film layers with lowrefractive index layers 1701 between them. Similarly, a yellowlightguide may be added, a cyan lightguide may be added or othercombinations of colors of lightguides may be used to increase the colorgamut of the display or provide a different predetermined color gamutsuch as one suitable for a night vision compatible display.

FIG. 18 is a top view of one embodiment of a light emitting device 1800comprising two light input couplers with two arrays of couplinglightguides 104 and two light sources 102 on the same edge in the middleregion oriented in opposite directions. As shown in FIG. 18, the +y and−y edges of the light emitting device 1800 may be very close to theborder of the light emitting region 108 because the light sources 102,including LEDs, do not extend past the bottom edge of the light emittingregion 108 as the light source 102 in the embodiment shown in FIG. 1does. Thus, a TV for example, illuminated by the light emitting device1800 of shown in FIG. 18 could have a light emitting display areaextending less than 2 millimeters from the edge of the light emittingdevice 1800 in the +y and −y directions. In the embodiment shown in FIG.18, the light source 102 is disposed substantially in a middle region ofthe light emitting region 108 between the +y and −y edges of the lightemitting device 1800.

FIG. 19 is a top view of one embodiment of a light emitting device 1900comprising one light input coupler with coupling lightguides 104 foldedin the +y and −y directions and then folded in the +z direction (out ofthe page in the drawing) toward a single light source 102.

FIG. 20 is a cross-sectional side view of one embodiment of a spatialdisplay 2000 with a rear polarizer 2002 of a liquid crystal displaypanel 2001 optically coupled to a film-based lightguide backlight 1402using an optical adhesive 801. The liquid crystal display panel 2001further comprises two display substrates 2003 (glass or a polymer filmfor example), liquid crystal material 2004, and a front polarizer 2005.The liquid crystal display panel may further comprise one or more of thefollowing: other suitable films, materials and/or layers such ascompensation films, alignment layers, color filters, coatings,transparent conductive layers, TFTs, anti-glare films, anti-reflectionfilms, etc. as is commonly known in the display industry.

FIG. 21 is a cross-sectional side view of one embodiment of a spatialdisplay 2100 comprising a frontlight 2103 optically coupled to areflective spatial light modulator 2101. The frontlight 2103 comprises afilm-based lightguide 2102 with light extracting features 1007 thatdirect light to the reflective spatial light modulator 2101 at anglesnear the surface normal of the reflective spatial light modulator 2101.In one embodiment, the reflective spatial light modulator 2101 is anelectrophoretic display, a microelectromechanical systems (MEMS)-baseddisplay, or a reflective liquid crystal display. In one embodiment, thelight extraction features 1007 direct one of 50%, 60%, 70%, 80%, and 90%of the light exiting the frontlight 2103 toward the reflective spatiallight modulator 2101 within an angular range of 60 degrees to 120degrees from the light emitting surface of the frontlight 2103.

FIG. 22 is a cross-sectional side view of one embodiment of a spatialdisplay 2200 comprising a frontlight 2202 with an air gap between afilm-based lightguide 2201 disposed adjacent to a reflective spatiallight modulator 2101. In one embodiment, the reflective spatial lightmodulator 2101 comprises one or more color filters. In anotherembodiment, the reflective spatial light modulator 2101 comprises one ormore spatial regions that reflect a wavelength bandwidth (FWHM) lessthan 300 nm and the spatial regions reflect more than one color in aspatial pattern, such as in an interferometric modulator or IMOD device.In another embodiment, the film-based lightguide 2201 is disposed toreceive light from two or more light sources with different colors suchthat the illumination is color sequential synchronized with thereflective spatial light modulator 2101 resulting in a full-colordisplay.

FIG. 23 is a cross-sectional side view of one embodiment of a spatialdisplay 2300 comprising a frontlight 2302 with light extraction features1007 on a side 2303 of the lightguide 2301 nearest the reflectivespatial light modulator 2101 optically coupled to a reflective spatiallight modulator 2101 using an optical adhesive 801.

FIG. 24 is a cross-sectional side view of one embodiment of a spatialdisplay 2400 comprising a frontlight 2404 comprising a film-basedlightguide 107 disposed within a reflective spatial light modulator 2401comprising a reflective component layer 2402. In one embodiment, thefilm-based lightguide 107 is a substrate for the reflective spatiallight modulator 2401. In another embodiment, the intensity of light forthe reflective spatial light modulator 2401 is controlled by frustratingthe total internal reflection occurring within the film-based lightguide107. In another embodiment, the intensity of light for a transmissivespatial light modulator (not shown) is controlled by frustrating thetotal internal reflection occurring within the film-based lightguide.

FIG. 25 is a cross-sectional side view of a region of one embodiment ofa light emitting device 2500 comprising a stack of coupling lightguides104 disposed adjacent a light source 102 with a substrate 2502 and alight collimating optical element 2501. In this embodiment, the lightcollimating optical 2501 element collimates light from the light sourcein a first plane (such as the x-z plane in the drawing) and second plane(y-x plane where the y-direction extends into the page) orthogonal tothe first plane. In one embodiment, the collimating optical element 2501is a lens which refracts and totally internally reflects light tocollimate light from a light emitting diode.

FIG. 26 is a perspective view of one embodiment of a light emittingdevice 2600 comprising a light source 102 and coupling lightguides 104oriented at an angle to the x, y, and z axes. The coupling lightguides104 are oriented at a first redirection angle 2601 from the +z axis(light emitting device optical axis), a second redirection angle 2602from the +x direction, and a third redirection angle 2603 from the +ydirection. In another embodiment, the light source optical axis and thecoupling lightguides 104 are oriented at a first redirection angle 2601from the +z axis (light emitting device optical axis), a secondredirection angle 2602 from the +x direction, and a third redirectionangle 2603 from the +y direction.

FIG. 27 is a perspective view of one embodiment of a light emittingdevice 2700 comprising coupling lightguides 104 that are opticallycoupled to a surface of a lightguide 107. In one embodiment, thecoupling lightguides optically coupled to the lightguide have athickness less than one selected from the group: 40%, 30%, 20%, 10%, and5% of the thickness of the lightguide.

FIG. 28 is a perspective view of one embodiment of a light emittingdevice 2800 comprising coupling lightguides 104 that are opticallycoupled to an edge 2801 of a lightguide 107. In one embodiment, thecoupling lightguides 104 optically coupled to the edge 2801 of thelightguide 107 have a thickness less than one selected from the group:90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10% of the thickness of thelightguide 107.

FIGS. 29a, 29b, 29c, 29d, and 29e illustrate one embodiment of a methodof manufacturing a lightguide 107 with continuously coupled lightguides104 using a light transmitting film. FIG. 29a is a perspective view ofone embodiment of a lightguide 107 continuously coupled to each couplinglightguide 104 in an array of coupling lightguides 104. The array ofcoupling lightguides 104 comprise linear fold regions 2902 substantiallyparallel to each other which further comprise relative positionmaintaining elements 2901 disposed within the linear fold regions 2902.In the configuration shown in FIG. 29a , the array of couplinglightguides are substantially within the same plane (x-y plane) as thelightguide 107 and the coupling lightguides 104 are regions of a lighttransmitting film. The total width, W_(t), of the array of the couplinglightguides in a direction substantially parallel to the linear foldregions 2902 is shown in FIG. 29a . In the embodiment shown in FIG. 29a, the coupling lightguides have substantially the same width, W_(s), ina direction 2906 parallel to the linear fold region. The direction 2903normal to a film surface 2980 at the linear fold region 2902 is shown inFIG. 29 a.

As shown in FIG. 29b , the linear fold regions 2902 are translated withrespect to each other from their locations shown in FIG. 29a . Thedistance between the two linear fold regions 2902 of the array ofcoupling lightguides 104 in a direction 2903 (parallel to the zdirection) perpendicular to the light transmitting film surface 2980 atthe linear fold region 2902 is increased. In addition, as shown in FIG.29b , the distance between the linear fold regions 2902 of the array ofcoupling lightguides 104 in a direction (y direction) substantiallyperpendicular to the direction 2906 of the linear fold region 2902 andparallel to the light transmitting film surface 2980 (x-y plane) at thelinear fold region 2902 is decreased.

As shown in FIG. 29c , the linear fold regions 2902 are translated withrespect to each other from their locations shown in FIG. 29b . In FIG.29c , the distance between the linear fold regions 2902 of the array ofcoupling lightguides 104 in a direction (x direction) substantiallyparallel to the direction 2906 of the linear fold regions 2902 andparallel to the light transmitting film surface 2980 at the linear foldregions 2902 is increased.

FIG. 29d illustrates further translation of the linear fold regions 2902where the distance between the linear fold regions 2902 of the array ofcoupling lightguides 104 in a direction (x direction) substantiallyparallel to the direction 2906 of the linear fold regions 2902 andparallel to the light transmitting film surface 2980 at the linear foldregions 2902 is increased and the distance between the linear foldregions 2902 of the array of coupling lightguides 104 in a direction2903 perpendicular to the light transmitting film surface 2980 at thelinear fold region 2902 is decreased.

As shown in FIG. 29e , the linear fold regions 2902 are translated withrespect to each other from their locations shown in FIG. 29d . In FIG.29e , the distance between the linear fold regions 2902 of the array ofcoupling lightguides 104 in a direction (x direction) substantiallyparallel to the direction 2906 of the linear fold regions 2902 andparallel to the light transmitting film surface 2980 at the linear foldregions 2902 is further increased from that of FIG. 29d and the distancebetween the linear fold regions 2902 of the array of couplinglightguides 104 in a direction 2903 perpendicular to the lighttransmitting film surface 2980 at the linear fold region 2902 is furtherdecreased over that of FIG. 29 d.

As a result of the translations of the linear fold regions 2902 as shownFIGS. 29a-e , corresponding edges 2981 of the linear fold regions 2902are separated by a distance, D. In one embodiment, the distance, D, isat least equal to the total width, W_(t), of the array of the couplinglightguides 104 in a direction substantially parallel to the linear foldregion 2902 In another embodiment, D=N×W_(s), where the array ofcoupling lightguides 104 comprise a number, N, of coupling lightguidesthat have substantially the same width, W_(s), in a direction parallelto the linear fold region 2902. The array of coupling lightguides 104disposed substantially one above another may be cut along a firstdirection 2904 to provide an array of input edges of the couplinglightguides 104 that end in substantially one plane perpendicular to thelinear fold regions 2902. The cut may be at other angles and may includeangled or arcuate cuts that can provide collimation or light redirectionof light from a light source disposed to couple light into the inputsurface of the coupling lightguides.

In a further embodiment, a method of manufacturing a light input couplerand lightguide comprises cutting the coupling lightguides such that twoinput couplers and two lightguides are formed from the same film. Forexample, by cutting the coupling lightguides along the direction 2904,the light transmitting film can be divided into two parts, eachcomprising a light input coupler and a lightguide.

FIG. 30 is a cross-sectional side view of a region of one embodiment ofa reflective display 3000 comprising a backlight 3028 with lightextraction features 1007 within the film-based lightguide disposedbetween two cladding layers 602. The backlight 3028 is disposed betweenthe light modulating pixels 3002 and the reflective element 3001 withinthe reflective display 3000. The light modulating pixels 3002 aredisposed between the red, green, and blue color filters 2822 and thebacklight 3028. Ambient light 3003 exterior to the display 3000propagates through the substrate 2823, through the color filters 2822,through the light modulating pixels 3002, through the backlight 3028,and reflects from the reflective element 3001 back through the backlight3028, the light modulating pixels 3002, the color filter 2822, thesubstrate 2823, and exits the reflective display 3000. Light 3004propagating within the core region 601 of the backlight 3028 isredirected by the light extraction features 1007 toward the reflectiveelement 3001. This light reflects back through the backlight 3028, thelight modulating pixels 3002, the color filters 2822 and the substrate2823 before exiting the reflective display 3000. In this embodiment, thebacklight 3028 is within a reflective spatial light modulator 3030. Inone embodiment, for example without limitation, the light modulatingpixels comprise liquid crystal materials, the reflective display furthercomprises polarizers, and the reflective layer is a reflective coatingon an outer surface of the cladding layer.

FIG. 31 is a top view of one of an input coupler and lightguide 3100with coupling lightguides 104 wherein the array of coupling lightguides104 has non-parallel regions. In the embodiment illustrated in FIG. 31,the coupling lightguides 104 have tapered region 3101 comprising lightcollimating edges 3181 and linear fold regions 2902 substantiallyparallel to each other. In another embodiment, the coupling lightguides104 have non-constant separations. In another embodiment, a method formanufacturing a lightguide 3100 with coupling lightguides 104 having atapered regions 3101 of the coupling lightguides 104 includes cuttingthe coupling lightguides in regions 3103 disposed at or near the taperedregion 3101 such that when the array of coupling lightguides 104 arefolded, the coupling lightguides 104 overlap to form a profiled,non-planar input surface that is capable of redirecting light inputthrough the light input surface so that the light is more collimated.

FIG. 32 is a perspective view of a portion of the lightguide 3100 withcoupling lightguides 104 shown in FIG. 31. The coupling lightguides 104have been cut in regions 3103 (shown in FIG. 31) disposed near thetapered region 3101 and folded such that the tapered regions 3101overlap to form a profiled light collimating edges 3181 that are capableof redirecting light input through the light input surface 103 so thatthe light is more collimated in the x-y plane within the film-basedlightguide 107.

FIG. 33 is a perspective view of one embodiment of a light input couplerand lightguide 3300 comprising a relative position maintaining element3301 disposed proximal to a linear fold region 2902. In this embodiment,the relative position maintaining element 3301 has a cross-sectionaledge 2971 in a plane (x-y plane as shown) parallel to the lighttransmitting film surface 2970 disposed proximal to the linear foldregion 2902 that comprises a substantially linear section 3303 orientedat an angle 3302 greater than 10 degrees to the direction 2906 parallelto the linear fold region 2902 for at least one coupling lightguide 104.In one embodiment, a substantially linear section 3303 is disposed at anangle of about 45 degrees to a direction parallel to the linear foldregion 2902.

FIGS. 34 and 35 a are top views of certain embodiments of light inputcouplers and lightguides 3400 and 3500, respectively, configured suchthat a volume and/or a size of the overall device is reduced whileretaining total internal reflection (TIR) light transfer from the lightsource (not shown) into the lightguide. In FIG. 34, the light inputcoupler and lightguide 3400 comprises bundles of coupling lightguides(3401 a, 3401 b) that are folded twice 3402 and recombined 3403 in aplane substantially parallel to the film-based lightguide 107.

FIG. 35a is a top view of one embodiment of a light emitting device witha light input coupler and lightguide 3500 that comprises bundles (3401a, 3401 b) that are folded upwards 3501 (+z direction) and combined in astack 3502 that is substantially perpendicular to the plane of thefilm-based lightguide 107.

FIG. 35b is a perspective view of the bundles (3401 a, 3401 b) ofcoupling lightguides folded upward 3501 in the +z direction. In anotherembodiment, the bundles are folded downwards (−z direction).

FIG. 36 is a top view of one embodiment of a light emitting device 3600comprising a lenticular lens array film 3601 with a linear array oflenticules 3602 wherein the lightguide region 106, light mixing region105, and the light input coupler 101 are formed from the lenticular lensarray film 3601.

FIG. 37 is a cross-sectional side view of one embodiment of a lenticularlens array film 3601 comprising light extraction features 1007 disposedon the core region 601 beneath the lenticules 3602 and the claddinglayer 602. A portion of the light 3702 propagating in the x directionand y direction within the core region 601 is directed into anglessmaller than the critical angle for the core-cladding interface by thelight extraction feature 1007 and passes through the cladding region 602and the lenticules 3602 where it is refracted by the lenticule 3602producing substantially collimated light 3701.

FIG. 38 is a cross-sectional side view of one embodiment of a display3800 comprising a multi-layer lenticular lens array film 3808 comprisinga red lightguide core region 3801 illuminated by a red LED (not shown),a green lightguide core region 3802 illuminated by a green LED (notshown), and a blue lightguide core region 3803 illuminated by a blue LED(not shown) and cladding regions 602. Red light 3804 incident on thelight extraction feature 1007 will be reflected toward the lenticules3602 which are light redirecting elements that substantially collimatethe light received from near their focal point and direct the lighttoward the pixels or sub-pixels corresponding to the red pixels 3810 ofthe display. Similarly, green light 3805 incident on the lightextraction feature 1007 will be reflected toward the lenticules 3602,collimated and directed toward the pixels or sub-pixels corresponding tothe green pixels 3811 of the display, and blue light 3806 incident onthe light extraction feature 1007 will be reflected toward thelenticules 3602, collimated and directed by the lenticules 3602 towardthe pixels or sub-pixels corresponding to the blue pixels 3812 of thedisplay. The focal lengths of the lenticules 3602 may be designed to beat the plane of the middle light extraction feature or another plane soas to optimize collimation of light. By using a common focal point, thelenticular lens array film is simpler to manufacture. In anotherembodiment, the focal point of the lenticular lens array film varies inthe y direction due to changing radii of curvature in the y direction.In a further embodiment, the focal point of the lenticular lens arrayfilm varies by height of the lenticule (constant radii of curvature butvarying the height of the lenticules). As shown in FIG. 38, the crosssection is of a lenticular lens array film 3808; however, similarcross-sections can be envisioned for microlens arrays which vary in twodimensional arrangements.

The display 3800 shown in FIG. 38 produces substantially collimatedlight output 3807 incident upon a liquid crystal display panel 3809comprising red pixel regions 3810, green pixel regions 3811, and bluepixel regions 3812. In this embodiment, the close proximity of thelightguides to the liquid crystal display panel and the collimation canpermit the elimination of color filters in the display panel. Colorfilters may be used to further eliminate any crosstalk or color filterspermitting more light through may be used. The lightguides may be formedseparately and combined together, then aligned with the liquid crystalpanel, the lightguides may be individually aligned with the panel, orthe lightguides may be formed at substantially the same time andsubsequently aligned to the panel, or the lightguides may be coupled tothe light panel and the light extraction features subsequently formed.In a further embodiment, the lightguide does not comprise a lenticularlens array film or light redirecting element.

FIG. 39 is a top view of an embodiment of a light emitting device 3900comprising a light input coupler 3908 comprising a lightguide 3903 and asingle coupling lightguide comprising fold regions 3909 defined by foldlines 3902, a reflective edge 3904 and a light input edge 204 disposedbetween a first reflective surface edge 3906 and a second reflectivesurface edge 3907 within a single film. The film of the light inputcoupler 3908 is folded along fold lines 3902 such that the fold regions3909 substantially overlay each other and the light source 102 coupleslight into each light input edge 204. The optical system is shown“un-folded” in FIG. 39 and the light sources 3901 correspond to thelocation of the light source 102 relative to the fold regions 3909 whenthe film is folded. As shown in FIG. 39, light 3905 from the lightsource 102 (and the light sources 3901 when folded) totally internallyreflects from the reflective edge 3904 which is angled toward the lightemitting region 108 of the lightguide 3903. The first reflective surface3906 and the second reflective surface 3907 are formed by shaped edges(angled or curved for example) in the film and serve to redirect aportion of light from the light sources (102 and 3901) into thelightguide at angles which totally internally reflect from the anglededge 3904.

FIG. 40 is a perspective view of the lightguide 3903 and the light inputcoupler 3908 comprising a light source 102 and coupling lightguide ofFIG. 39 as the film is being folded along the fold lines 3902 in thedirection 4001 represented in the figure. The fold regions 3909substantially layer upon each other such that the light input edges 204stack and align to receive light from the light source 102.

FIG. 41 is a perspective view of the lightguide 3903 and the light inputcoupler 3908 of FIG. 39 folded and comprising a coupling lightguideformed from overlapping fold regions 3909 of a film lightguide 3903. Thefold regions 3909 substantially layer upon each other such that thelight input edges 204 stack and align to receive light from the lightsource 102.

FIG. 42 is an elevated view of an embodiment film-based lightguide 4205comprising a first light emitting region 4201 disposed to receive lightfrom a first set of coupling lightguides 4203 and a second lightemitting region 4202 disposed to receive light from a second set ofcoupling lightguides 4204. The light emitting regions are separated fromeach other in the y direction by a distance “SD” 4206. The free ends ofthe sets of coupling lightguides 4203 and 4204 can be folded toward the−y direction such that both sets substantially overlap as shown in FIG.43.

FIG. 43 is an elevated view of the film-based lightguide 4205 of FIG. 42wherein the coupling lightguides 4203 are folded such that theysubstantially overlap and form a light input surface 103. In thisembodiment, a single light source (not shown) may illuminate twoseparate light emitting regions within the same film. In anotherembodiment, two separated film-based lightguides have separate lightinput couplers which are folded and the light input edges are broughttogether to form a stack of coupling lightguides disposed to receivelight from a light source. This type of configuration may be useful, forexample, where the first light emitting region backlights a LCD and thesecond light emitting region illuminates a keypad on a mobile phonedevice.

FIG. 44 is a cross-sectional side view of one embodiment of a lightemitting device 4400 with optical redundancy comprising two lightguides107 stacked in the z direction. Light sources and coupling lightguideswithin the holders 4402 arranged substantially adjacent in the ydirection direct light into core regions 601 such that light 4401 isoutput from the light emitting region 108 from each lightguide 107.

FIG. 45 is a cross-sectional side view of one embodiment of a lightemitting device 4500 with a first light source 4501 and a second lightsource 4502 thermally coupled to a first thermal transfer element 4505(such as a metal core printed circuit board (PCB)) and thermallyinsulated (physically separated by an air gap in the embodiment shown)from a second thermal transfer element 4506 that is thermally coupled toa third light source 4503 and a fourth light source 4504. The firstlight source 4501 and the third light source 4503 are disposed to couplelight into a first light input coupler 4507 and the second light source4502 and the fourth light source 4504 are disposed to couple light intoa second light input coupler 4508. In this embodiment, the heatdissipated from the first light source 4501 is dissipated along thefirst thermal transfer element 4505 in the x direction toward the secondlight source 4502 such that heat from the first light source 4501 doesnot substantially increase the temperature at the third light source4503 by conduction.

FIG. 46 is a top view of one embodiment of a light emitting device 4600comprising a plurality of coupling lightguides 104 with a plurality offirst reflective surface edges 3906 and a plurality of second reflectivesurface edges 3907 within each coupling lightguide 104. In theembodiment shown in FIG. 46, three light sources 102 are disposed tocouple light into respective light input edges 204 at least partiallydefined by respective first reflective surface edges 3906 and secondreflective surface edges 3907.

FIG. 47 is an enlarged perspective view of the coupling lightguides 104of FIG. 46 with the light input edges 204 disposed between the firstreflective surface edges 3906 and the second reflective surface edges3907. The light sources 102 are omitted in FIG. 47 for clarity.

FIG. 48 is a cross-sectional side view of the coupling lightguides 104and the light source 102 of one embodiment of a light emitting device4800 comprising index matching regions 4801 disposed between the coreregions 601 of the coupling lightguides 104 in the index-matched region4803 of the coupling lightguides 104 disposed proximate the light source102. The light source 102 is positioned adjacent the couplinglightguides 104 and the high angle light 4802 from the light source 102propagates through the coupling lightguides 104 and the index matchingregion 4801 and is coupled into the coupling lightguides 104 at alocation distant from the light input edge 204 of the couplinglightguides 104. In the embodiment shown in FIG. 48, the light from thelight source 102 is coupled into more coupling lightguides because thelight, for example at 60 degrees from the optical axis 4830 of the lightsource 102 propagates into a core region 601 near the light source,propagates through the index matching region 4801, and totallyinternally reflects in a core region 601 further away from the lightsource 102. In this embodiment, a portion of the light is coupled intothe outer coupling lightguides 104 that would not normally receive thelight if there were cladding present at or near the light input edge204.

FIG. 49 is a top view of one embodiment of a film-based lightguide 4900comprising an array of tapered coupling lightguides 4902 formed bycutting regions in a lightguide 107. The array of tapered couplinglightguides 4902 extend in a first direction (y direction as shown) adimension, d1, which is less than a parallel dimension, d2, of the lightemitting region 108 of the lightguide 107. A compensation region 4901 isdefined within the film-based lightguide 4900 which does not includetapered coupling lightguides 4902 (when the tapered coupling lightguides4902 are not folded or bent). In this embodiment, the compensationregion provides a volume having sufficient length in the y direction toplace a light source (not shown) such that the light source does notextend past the lower edge 4903 of the lightguide 107. The compensationregion 4901 of the light emitting region 108 may have a higher densityof light extraction features (not shown) to compensate for the lowerinput flux directly received from the tapered coupling lightguides 4902into the light emitting region 108. In one embodiment, a substantiallyuniform luminance or light flux output per area in the light emittingregion 108 is achieved despite the lower level of light flux received bythe light extraction features within the compensation region 4901 of thelight emitting region by, for example, increasing the light extractionefficiency or area ratio of the light extraction features to the areawithout light extraction features within one or more regions of thecompensation region, increasing the width of the light mixing regionbetween the coupling lightguides and the light emitting region,decreasing the light extraction efficiency or the average area ratio ofthe light extraction features to the areas without light extractionfeatures in one or more regions of the light emitting region outside thecompensation region, and any suitable combination thereof.

FIG. 50 is a perspective top view of one embodiment of a light emittingdevice 5000 comprising the film-based lightguide 4900 shown in FIG. 49and a light source 102. In this embodiment, tapered coupling lightguides4902 are folded in the −y direction toward the light source 102 suchthat the light input edges 204 of the coupling lightguides 4902 aredisposed to receive light from the light source 102. Light from thelight source 102 propagating through the tapered coupling lightguides4902 exits the tapered coupling lightguides 4902 and enters into thelight emitting region 108 generally propagating in the +x directionwhile expanding in the +y and −y directions. In the embodiment shown inFIG. 50, the light source 102 is disposed within the region that did notcomprise a tapered coupling lightguide 4902 and the light source 102does not extend in the y direction past a lower edge 4903 of the lightemitting device 5000. By not extending past the lower edge 4903, thelight emitting device 5000 has a shorter overall width in the ydirection. Furthermore, the light emitting device 5000 can maintain theshorter dimension, d1, in the y direction (shown in FIG. 49) when thetapered coupling lightguides 4902 and the light source 102 are foldedunder (−z direction and then +x direction) the light emitting region 108along the fold (or bend) line 5001.

FIG. 51 is a perspective view of an embodiment light emitting device5100 comprising the light emitting device 5000 shown in FIG. 50 with thetapered coupling lightguides 4902 and light source 102 shown in FIG. 50folded (−z direction and then +x direction) behind the light emittingregion 108 along the fold (or bend) line 5001. As can be seen from FIG.51, a distance between the lower edge of the light emitting region 108and the corresponding edge of the light emitting device 4903 in the −ydirection is relatively small. When this distance is small, the lightemitting region 108 can appear borderless, and for example, a displaycomprising a backlight where the light emitting region 108 extends veryclose to the edge of the backlight can appear frameless or borderless.

FIG. 52 is a top view of one embodiment of a film-based lightguide 5200comprising an array of angled, tapered coupling lightguides 5201 formedby cutting regions in a lightguide 107 at a first coupling lightguideorientation angle, γ, defined as the angle between the couplinglightguide axis 5202 and the direction 5203 parallel to the majorcomponent of the direction of the coupling lightguides 5201 to the lightemitting region 108 of the lightguide 107. By cutting the taperedcoupling lightguides 5201 within the lightguide 107 at a first couplinglightguide orientation angle, the angled, tapered lightguides 5201, whenfolded, provide volume with a dimension of sufficient length to place alight source such that the light source does not extend past the loweredge 4903 of the film-based lightguide 5200.

FIG. 53 is a perspective view of one embodiment of a light emittingdevice 5300 comprising the film-based lightguide 5200 shown in FIG. 52and a light source 102. As shown in FIG. 53, the angled, taperedcoupling lightguides 5201 are folded in the −y direction toward thelight source 102 such that the light input surfaces 204 of the stackedcoupling lightguides 5201 are disposed to receive light from the lightsource 102.

FIG. 54 is a top view of one embodiment of a film-based lightguide 5400comprising a first array of angled, tapered coupling lightguides 5201formed by cutting regions in the lightguide 107 at a first couplinglightguide orientation angle 5406 and a second array of angled, taperedcoupling lightguides 5402 formed by cutting regions in the lightguide107 at a second coupling lightguide orientation angle 5407. By cuttingthe first array of coupling lightguides 5201 and the second array ofcoupling lightguides 5402 within the lightguide 107 at the firstcoupling lightguide orientation angle 5406 and the second couplinglightguide orientation angle 5407, respectively, the angled, taperedlightguides 5201 and 5402, when folded, provide volume with a dimensionof sufficient length to place one or more light sources 102 such thatthe one or more light sources 102 do not extend past the lower edge 4903of the lightguide 107.

FIG. 55 is a perspective top view of one embodiment of a light emittingdevice 5500 comprising the film-based lightguide 5400 shown in FIG. 54and a light source 102 emitting light in the +y direction and −ydirection (such as two LEDs disposed back to back). The first array ofcoupling lightguides 5201 are folded in the −y direction toward thelight source 102 such that each light input surface 204 is disposed toreceive light from the light source 102 and the second array of couplinglightguides 5402 are folded in the +y direction toward the light source102 such that each light input surface 204 is disposed to receive lightfrom the light source 102. The first and second array of couplinglightguides 5201 and 5402 are angled away from the center of the lightemitting region 108 to allow the light source 102 to be disposed in thecentral region of the lightguide 107 (in the y direction) such that thelight source 102 does not extend past the lower edge 4903 or upper edge5401 of the lightguide 107. The light source 102, the first array ofcoupling lightguides 5201, and the second array of coupling lightguides5402 may be folded under the light emitting region 108 along the fold(or bend) axis 5001 such that the light emitting device 5500 issubstantially edgeless or has light emitting regions extending veryclose to the edges of the light emitting device in the x-y plane.

FIG. 56 is a top view of one embodiment of a light emitting device 5600comprising the lightguide 107, the coupling lightguides 104 and a mirror5601 functioning as a light redirecting optical element including acurved or arcuate reflective surface or region disposed to redirectlight from the light source 102 into the coupling lightguides 104.Within the coupling lightguides 104, the light propagates through thecoupling lightguides 104 into the lightguide 107 and exits thelightguide 107 in the light emitting region 108.

FIG. 57 is a top view of one embodiment of a light emitting device 5700comprising the lightguide 107, the coupling lightguides 104 and a mirror5701. In this embodiment, mirror 5701 includes two or more curved orarcuate surfaces or regions disposed to redirect light from one or morelight sources, such as the two light sources 102 shown in FIG. 57, intothe coupling lightguides 104 where the mirror is functioning as abidirectional light turning optical element. Within the couplinglightguides 104, the light propagates through the coupling lightguides104 into the lightguide 107 and exits the lightguide 107 in the lightemitting region 108. As shown in FIG. 57, the light sources 102 aredisposed to emit light with a corresponding light source optical axis5702 substantially oriented parallel to the +x direction. The curvedmirror redirects the light into axis 5703 oriented in the +y and 5704oriented in the −y direction. In another embodiment, the optical axes ofthe light sources 102 are oriented substantially in the −z direction(into the page) and the curved mirror redirects the light into axes 5703and 5704 oriented in the +y and −y directions, respectively.

FIG. 58 is a top view of one embodiment of a light emitting device 5800comprising the lightguide 107 and coupling lightguides 104 on oppositesides of the lightguide 107 that have been folded behind the lightemitting region 108 of the light emitting device 5800 along the lateralsides 5001 (shown by phantom lines in FIG. 58) such that the frames orborder regions (5830, 5831) between the light emitting region 108 andthe corresponding edge (5001, 5832) of the light emitting device 5800 inthe +x direction, −x direction, and +y direction are minimized and thelight emitting device 5800 can be substantially edgeless (or have asmall frame) along any desirable number of sides or edges, such as threesides or edges as shown in FIG. 58.

FIG. 59 is a top view of one embodiment of a light emitting device 5900comprising the lightguide 107, with the coupling lightguides 104 on twoorthogonal sides. In this embodiment, a light coupling optical element5901 is disposed to increase the light flux that couples from the lightsource 102 into the two sets of coupling lightguides 104. A firstportion of the light 5902 from the light source 102 will refract uponentering the light coupling optical element 5901 and be directed into awaveguide condition within the coupling lightguides 104 orientedsubstantially parallel to the x axis and a second portion of the light5903 will refract upon entering the light coupling optical element 5901and be directed into a waveguide condition within the couplinglightguides 104 oriented substantially parallel to the y axis.

FIG. 60 is a cross-sectional side view of a portion of one embodiment ofa light emitting device 6000 comprising the lightguide 107 and the lightinput coupler 101. In this embodiment, a low contact area cover 6001 isoperatively coupled, such as physically coupled as shown in FIG. 60, tothe light input coupler 101 (or one or more elements within the lightinput coupler 101) and wraps around the light input coupler 101 and isphysically coupled or maintained in a region near the lightguide 107 bya suitable fastening mechanism, such as one or more fibers 6002 thatstitches the low contact area cover 6001 in contact or in proximity tothe lightguide 107. In the embodiment shown in FIG. 60, the stitchespass through the low contact area cover 6001 and the lightguide 107 andprovide a very small surface area in the primary direction (−xdirection) of propagation of the light within the light emitting portionof the lightguide 107. A physical coupling mechanism with a smallsurface within the lightguide reduces the scattering or reflection oflight propagating within the lightguide which can reduce opticalefficiency or cause stray light. In the embodiment shown in FIG. 60, thefiber (or wire, thread, etc.) 6002 provides a low contact area physicalcoupling mechanism that has a small percentage of cross sectional areain the y-z plane (orthogonal to the optical axis direction (−xdirection) of the light within the lightguide region).

FIG. 61 shows an enlarged view of a region of the lightguide 107 shownin FIG. 60 in which the lightguide 107 is in contact with the lowcontact area cover 6001. In this embodiment, the low contact area cover6001 has convex surface features 6101 that reduce the contact area 6102in contact with the surface 6103 of the lightguide 107 disposed near thelow contact area cover 6101. In other embodiments, the low contact areacover 6001 includes any suitable feature that reduces the contact area6102.

FIG. 62 is a side view of a portion of one embodiment of a lightemitting device 6200 comprising the lightguide 107 and couplinglightguides 104 protected by a low contact area cover 6001. The lowcontact area cover 6001 is operatively coupled, such as physicallycoupled as shown in FIG. 62, by a suitable fastening mechanism, such asone or more sewn fibers 6002, to the lightguide 1007 at two or moreregions of the low contact area cover 6001 such that the low contactarea cover wraps around the coupling lightguides 104. A non-adjustablecylindrical tension rod 6205 and an adjustable cylindrical tension rod6201 are disposed substantially parallel to each other in the ydirection and are operatively coupled, such as physically coupled by twobraces 6202 that are substantially parallel to each other in the xdirection. The inner surface 6101 of the low contact area cover 6001comprises convex surface features. When the cylindrical tension rod 6201is translated in the +x direction, the inner surface 6101 of the lowcontact area cover 6001 is pulled inward in the +z and −z directionsonto the lightguide 107 and coupling lightguide 104. The surface relieffeatures on the low contact area cover 6001 reduce the amount of lightlost from within the coupling lightguide 104 and/or the lightguide 107when the cylindrical tension rod 6201 is translated in the +x direction.Translating the tension rod in the +x direction also reduces a height ofthe light emitting device 6200 parallel to the z direction by moving thecoupling lightguides 104 closer together and closer to the lightguide107. The low contact area cover 6001 also provides protection from dustcontamination and physical contact by other components coupling lightout of the coupling lightguides 104 and/or the lightguide film 107.

FIG. 63 is a perspective view of a portion of one embodiment of afilm-based lightguide 6300 comprising coupling lightguides 6301including one or more flanges. In this embodiment, each couplinglightguide 6301 includes a flange 6306 on each opposing side of an endregion 6307 of the coupling lightguides 6301 as shown in FIG. 63. Astrap 6302 is guided through two slits 6303 formed in a base 6304 andpulled by both ends in the y directions (or in the +y direction, forexample, if the region of the strap in the −y direction is held fixedrelative to the base 6304). By tightening the strap 6302, the couplinglightguides 6301 are urged closer together and toward the base 6304 inthe z direction to facilitate securing the coupling lightguides 6301with respect to the base 6304. Also, the strap 6303 and the hook regionsformed by the flanges 6306 prevent or limit the coupling lightguides6301 from translating in the −x direction. In one embodiment, after thecoupling lightguides 6301 are urged together, the end region 6307 of thecoupling lightguides 6301 and/or the flanges 6306 are cut or otherwiseremoved along a cut axis 6305. The resulting new edge at the end of thecoupling lightguides 6301 along the cut axis 6305 can be an inputsurface or otherwise coupled to an optical element or polished to form anew input surface for the coupling lightguides 6301. The ends may bephysically or optically coupled to a window or an adhesive or epoxy suchas an Ultraviolet (UV) curable epoxy disposed between the ends of thecoupling lightguide 6301 and a high gloss fluorinated ethylene propylene(FEP) film or polished glass such that the film or glass can be removed,leaving a glossy, polished input surface made of the epoxy which alsohelps holds the ends of the coupling lightguides 6301 together. Inanother embodiment, the holding mechanism is removed after one or moreof the coupling lightguides 6301 are adhered together or to anothercomponent of the light emitting device 6300. In another embodiment, theend region 6307 is not removed from the coupling lightguides 6301 andthe ends of the coupling lightguides 6301 form the light input surface204 as shown in FIG. 63.

FIG. 64 is a perspective view of one embodiment of a film-basedlightguide 6400 comprising a light input coupler and lightguide 107comprising a relative position maintaining element 3301 disposedproximal to a linear fold line or region. In this embodiment, therelative position maintaining element 3301 has a cross-sectional guideedge in a plane (x-y plane as shown) parallel to the lightguide 107 thatcomprises a substantially linear angled guide edge 3303 oriented at anangle 3302 about 45 degrees to the direction 6404 (+y direction)parallel to the linear fold direction (the −y direction). If thecoupling lightguide 6401 is folded without the relative positionmaintaining element 3301, the stress point for the force of the fold orbend pulling the coupling lightguide in the −y direction is at theregion 6402 near where the coupling lightguide 6401 separates from thelightguide 107. By using the relative position maintaining element 3301,when the coupling lightguide 6401 is pulled in the −y direction, theforce is distributed across a length region 6403 of the angled guideedge 3303 of the relative position maintaining element 3301. In oneembodiment, the angled guide edges 3303 on the relative positionmaintaining element 3301 reduce the likelihood of tearing the couplinglightguide 6401 and enable a lower profile (reduced height in the zdirection) because the coupling lightguide 6401 can be pulled withrelatively more force. In another embodiment, the thickness and edgeprofile of the relative position maintaining element 3301 dictates aminimum bend radius for the fold in the coupling lightguide 6401 nearthe length region 6403.

FIG. 65 is a perspective view of one embodiment of a relative positionmaintaining element 6501 comprising rounded angled edge surfaces 6502.By rounding the edge surfaces 6502, the surface area of contact with afolded film is increased to the rounded angled edge surface 6502. Byspreading the force of pull in the −y direction over a larger area ofthe coupling lightguide 6401, for example, the coupling lightguide 6401is less likely to fracture or tear.

FIG. 66 is a perspective view of one embodiment of a relative positionmaintaining element 6600 comprising rounded angled edge surfaces 6502and rounded tips 6601. By rounding the edge surfaces 6502, the surfacearea of contact with a folded film is increased to the rounded anglededge surface 6502. By spreading the force of pull in the −y directionover a larger area of the coupling lightguide 6401, for example, thecoupling lightguide 6401 is less likely to fracture or tear. By roundingthe tips 6601 of the relative position maintaining element 6600, theedge is less sharp and less likely to induce a localized stress regionin the coupling lightguide 6401 as the coupling lightguide 6401 isfolded (or bent) or while maintaining the fold or bend.

FIG. 67 is a perspective view of a portion of one embodiment of afilm-based lightguide 6700 comprising coupling lightguides 6301including one or more flanges 6306. In this embodiment, each couplinglightguide 6301 includes a flange 6306 on each opposing side of an endregion 6307 of the coupling lightguides 6301 as shown in FIG. 63. Astrap 6302 is guided through two slits 6303 in a base 6304 and pulled byboth ends in the y directions (or in the +y direction, for example, ifthe region of the strap in the −y direction is held fixed relative tothe base 6304). By tightening the strap 6303, the coupling lightguides6301 are urged closer together and toward the base 6304 in the zdirection to facilitate securing the coupling lightguides 6301 withrespect to the base 6304. Also, the strap 6303 and the hook regionsformed by the flanges 6306 prevent or limit the coupling lightguides6301 from translating in the −x direction. In one embodiment, after thecoupling lightguides 6301 are urged together, the end region 6307 of thecoupling lightguides 6301 and/or the flanges 6306 are cut or otherwiseremoved along an aperture cut 6701 by tearing or cutting the regionsbetween the aperture cut 6701 and the flanges 6306 along a cut axis6305. An edge 6702 of the aperture cut 6701 then becomes the light inputsurface of the coupling lightguides 6301. For example, in oneembodiment, the cutting device used to cut the coupling lightguides 6301from a film can also cut the light input surface on the couplinglightguides and the flanges 6306 and strap 6302 assist with assembly.

FIG. 68 is a perspective view of a portion of one embodiment of thelight emitting device 6200 illustrated in FIG. 62 comprising thelightguide 107 and light input coupler protected by a low contact areacover 6001. In this embodiment, the low contact area cover 6001 isphysically coupled by a fiber 6002 to the lightguide 1007 in two regionsof the low contact area cover 6001 by passing a fiber 6002 through thetwo layers of the low contact area cover 6001 and the lightguide 107 ina sewing or threading type action.

FIG. 69 is a top view of one embodiment of a light emitting device 6900with two light input couplers comprising coupling lightguides 104 and afirst light source 6902 and a second light source 6903 disposed onopposite sides of the lightguide 107. An aluminum bar type thermaltransfer element 6901 is disposed to thermally couple heat from thefirst light source 6902 and the second light source 6903 and dissipateheat along the length of light emitting device 6900 in the x direction.In other embodiments, one or more suitable thermal transfer elements maybe incorporated into the light emitting device 6900 to facilitatedissipating heat from the light emitting device 6900.

FIG. 70 is a perspective view of one embodiment of a light emittingdevice 7000 comprising the lightguide 107, the light input coupler 101,and a light reflecting film 7004 disposed between the light inputcoupler 101 and the light emitting region 108. A circuit board 7001 forthe light source in the light input coupler 101 couples heat from thelight source to a thermal transfer element heat sink 7002 thermallycoupled to the circuit board 7001. In this embodiment, the thermaltransfer element 7002 comprises fins 7003 and is extended in the x-yplane behind the light reflecting film 7004 and the light emittingregion 108 to provide an increased surface area and occupy a volume thatdoes not extend past the edges 7030 of the lightguide 107 to conductheat away from the circuit board 7001 and the light source in the lightinput coupler 101.

FIG. 71 is a top view of a region of one embodiment of a light emittingdevice 7100 comprising a stack 7101 of coupling lightguides disposed toreceive light from a light collimating optical element 7102 and thelight source 102. The output surface 7103 of the light collimatingoptical element 7102 corresponds in shape to the light input surface7105 of the stack 7101 of coupling lightguides. Light 7104 from thelight source 102 is collimated by the light collimating optical element7102 and enters the stack 7101 of coupling lightguides. For example, asshown in FIG. 71, the output surface 7103 has a rectangular shapesubstantially matching the rectangular shape of the light input surface7105 of the stack 7101 of coupling lightguides.

FIG. 72 is a cross-sectional side view of the light emitting device 7100shown in FIG. 71. The light 7104 collimated by the light collimatingoptical element 7102 enters the stack 7101 of coupling lightguides 7201.

FIG. 73 is a top view of one embodiment of a light emitting device 7300comprising the stack 7101 of coupling lightguides physically coupled tothe light collimating optical element 7102. The physical coupling regionof the stack 7101 of coupling lightguides defines a cavity 7331 withinwhich the light collimating optical element physical coupling region7302 is disposed. In the embodiment shown, the light collimating opticalelement physical coupling region 7302 is a ridge 7330 on the lightcollimating optical element 7102 and the physical coupling region of thestack 7101 of coupling lightguides is the region 7301 partiallysurrounding an opening or aperture cut within each coupling lightguidewhich, when stacked, forms a cavity 7331 that substantially constrainsand aligns the light collimating element 7102 in the x and y directions.

FIG. 74 is a top view of a region of one embodiment of a light emittingdevice 7400 comprising a light turning optical element 7401 opticallycoupled using an index matching adhesive 7402 to a stack 7101 ofcoupling lightguides. Light 7403 from the light source 102 totallyinternally reflects off of the light turning surface 7405 of the lightturning optical element 7401, passes through the index matching adhesive7402 and into the stack 7101 of coupling lightguides and the opticalaxis of the light 7403 from the light source 102 is rotated. Light 7404from the light source 102 passes directly into the stack 7101 ofcoupling lightguides without reflecting off of the light turning surface7405 of the light turning optical element 7401.

FIG. 75a is a top view of a region of one embodiment of a light emittingdevice 7500 comprising the light source 102 disposed adjacent a lateraledge 7503 of a stack 7501 of coupling lightguides with light turningoptical edges 7502. The light turning optical edges 7502 reflect aportion of the incident light from the light source 102 with an opticalaxis 7504 in a first direction (−y direction, for example) such that theoptical axis 7504 is rotated from the first direction by an angle 7506to an optical axis 7505 in a second direction (−x direction, forexample).

FIG. 75b is a top view of a region of one embodiment of a light emittingdevice 7530 comprising the light source 102 disposed adjacent the lightinput surface edge 7507 of the extended region 7508 of the stack 7501 ofcoupling lightguides with light turning optical edges 7502. In thisembodiment, the extended region 7508 allows the light input surface edge7507 to be cut, trimmed, and/or polished (separately or as a collectionof coupling lightguides in a stack) or bonded to a light collimatingoptical element without damaging (scratching or tearing, for example) orunnecessarily coupling light out of the lateral edges 7503 of the stack7501 of coupling lightguides (with overflow adhesive, for example).

FIG. 76 is a top view of a region of one embodiment of a light emittingdevice 7600 comprising the light source 102 disposed to couple lightinto two light turning optical elements 7401 optically coupled using anadhesive 7402 (such as an index matching adhesive or optical adhesivefor example) to two stacks 7101 of coupling lightguides.

FIG. 77 is a top view of a region of one embodiment of a light emittingdevice 7700 comprising the light source 102 disposed to couple lightinto a bi-directional light turning optical element 7701 opticallycoupled using index matching adhesive 7402 to two stacks 7101 ofcoupling lightguides. In this embodiment, a single bi-directional lightturning optical element 7701 divides and rotates the optical axis oflight from a single light source in a first direction (−y direction)into two different directions (−x and +x directions), replaces twounidirectional light turning optical elements, and reduces part countand associated costs.

FIG. 78 is a top view of a region of one embodiment of a light emittingdevice 7800 comprising two light sources 102 disposed to couple lightinto a bi-directional light turning optical element 7801 opticallycoupled using index matching adhesive 7402 to two stacks 7101 ofcoupling lightguides. In this embodiment, a single bi-directional lightturning optical element 7701 is designed to divide and rotate theoptical axes of light from two light sources from a first direction (−ydirection) to two different directions (+x and −x directions).

FIG. 79 is a top view of a region of one embodiment of a light emittingdevice 7900 comprising the light source 102 disposed to couple lightinto two stacks 7501 of coupling lightguides with light turning opticaledges 7502. In this embodiment, the two stacks 7501 of couplinglightguides divide and rotate the optical axis of light from the lightsource from a first direction (−y direction) to two different directions(+x and −x directions).

FIG. 80 is a top view of a region of one embodiment of a light emittingdevice 8000 comprising the light source 102 disposed to couple lightinto two overlapping stacks 7501 of coupling lightguides with lightturning optical edges 7502. In this embodiment, the two stacks 7501 ofcoupling lightguides divide and rotate the optical axis of light fromthe light source from a first direction (−y direction) to two differentdirections (+x and −x directions).

FIG. 81 is a top view of a region of one embodiment of a light emittingdevice 8100 comprising the light source 102 disposed to couple lightinto the stack 7501 of coupling lightguides with light turning opticaledges 7502. In this embodiment, the stack 7501 of coupling lightguideshas tabs 8102 with tab alignment openings or apertures 8101. The tabalignment openings or apertures 8101 may be used, for example, toregister the stack 7501 of coupling lightguides (and their light inputsurface) with a pin extending from a circuit board comprising a lightsource to enable efficient light coupling into the stack 7501 ofcoupling lightguides.

FIG. 82 is a top view of a region of one embodiment of a light emittingdevice 8200 comprising the light source 102 disposed to couple lightinto the stack 7501 of coupling lightguides with light turning opticaledges 7502. In this embodiment, the stack 7501 of coupling lightguidehas alignment openings or apertures 8201 in low light flux densityregions 8202. The alignment openings or apertures 8201 may be used, forexample, to register the stack 7501 of coupling lightguides to the lightsource 102 and they are located in a low light flux density region 8202such that a tab is not needed and any light loss due to the location ofthe alignment openings or apertures 8201 within the stack 7501 ofcoupling lightguides is minimized.

FIG. 83 is a top view of a region of one embodiment of a light emittingdevice 8300 comprising the light source 102 disposed to couple lightinto the stack 7501 of coupling lightguides with a light source overlaytab region 8301 comprising an alignment cavity 8302 for registration ofthe light input surface 8303 of the stack 7501 of coupling lightguideswith the light source 102. In this embodiment, for example, thealignment cavity 7501 within the stack 7501 of coupling lightguides maybe placed over the light source 102 such that a light input surface 8303of the stack 7501 of coupling lightguides is substantially registeredand aligned in the x and y directions with the light source 102.

FIG. 84 is a top view of one embodiment of a lightguide 8400 comprisingthe film-based lightguide 107 having coupling lightguides 8401 withlight turning optical edges 7502. The coupling lightguides 8401 can befolded in the +z direction and translated laterally in the +x direction8402 (shown folded in FIG. 85) such that the coupling lightguides 8401stack and align above one another.

FIG. 85 is a top view of one embodiment of a light emitting device 8500comprising the lightguide 8400 shown in FIG. 84 with the couplinglightguides 8401 folded and translated to form the stack 7501 ofcoupling lightguides 8401 such that the stack 7501 extends past alateral edge 8501 of the lightguide region 106 of the film-basedlightguide 107. Light 8502 from the light source 102 has an optical axisin the −y direction that is rotated by the light turning optical edges7502 of the stack 7501 of coupling lightguides to the −x direction andthe fold in the stack 7501 of coupling lightguides 8401 redirects thecoupling lightguide orientation to the −y direction such that the lighthas an optical axis exiting the coupling lightguides in the −ydirection. The light 8502 then propagates into the lightguide region 106of the film-based lightguide 107 and exits the film-based lightguide 107in the light emitting region 108.

FIG. 86 is a top view of one embodiment of a lightguide 8600 comprisingthe film-based lightguide 107 having coupling lightguides 8401 withlight turning optical edges 7502 and a non-folded coupling lightguide8603. The non-folded coupling lightguide 8603 has a width 8601 along theedge of the lightguide region 106 from which the coupling lightguides8401 extend and a length 8602 in the direction perpendicular to the edgewhere the coupling lightguides 8401 connect with the lightguide region106.

FIG. 87 is a top view of one embodiment of a light emitting device 8700comprising the lightguide 8600 shown in FIG. 86 with the couplinglightguides 8401 folded and translated to form the stack 7501 ofcoupling lightguides 8401 that do not extend past the lateral edge 8501(or a plane comprising the lateral edge 8501) of the lightguide region106 of the film-based lightguide 107. Light 8502 from the light source102 has an optical axis in the −y direction that is rotated by the lightturning optical edges 7502 of the stack 7501 of coupling lightguides8401 to the −x direction, and the fold in the stack 7501 of couplinglightguides 8401 redirects the coupling lightguide orientation to the −ydirection such that the light has an optical axis exiting the couplinglightguides 8401 in the −y direction. The light 8502 then propagatesinto the lightguide region 106 and exits the film-based lightguide 107in the light emitting region 108. Light 8702 from the light source 102has an optical axis in the −y direction and passes through thenon-folded coupling lightguide 8603 and into the lightguide region 106directly. In this embodiment, the non-folded coupling lightguide 8603permits the stack 7501 of coupling lightguides 8401 to not extend pastthe lateral edge 8501 of the lightguide region 106 of the film-basedlightguide 107 because the non-folded coupling lightguide 8603 does notneed to be folded and translated in the +x direction to receive lightfrom the light source 102.

FIG. 88 is a top view of one embodiment of a lightguide 8800 comprisingthe film-based lightguide 107 having coupling lightguides 8801 withlight turning optical edges 8803 and light collimating optical edges8802. The coupling lightguides 8801 can be folded in the +z directionand translated laterally in the +x direction 8402 (shown folded in FIG.89) such that the coupling lightguides 8801 stack and align above oneanother.

FIG. 89 is a top view of one embodiment of a light emitting device 8900comprising the lightguide 8800 shown in FIG. 88 with the couplinglightguides 8801 folded and translated to form a stack 8902 of couplinglightguides 8801 such that the stack 8902 of coupling light guides 8801extends past a lateral edge 8501 of the lightguide region 106 of thefilm-based lightguide 107. Light 8901 from the light source 102 iscollimated by the light collimating optical edges 8802 and has anoptical axis in the −y direction that is rotated by the light turningoptical edges 8803 of the stack 8902 of coupling lightguides 8801 to the−x direction and the fold in the stack 8902 of coupling lightguides 8801redirects the coupling lightguide orientation to the −y direction suchthat the light has an optical axis exiting the coupling lightguides 8801in the −y direction. The light 8901 then propagates into the lightguideregion 106 of the film-based lightguide 107 and exits the film-basedlightguide 107 in the light emitting region 108.

FIG. 90 is a top view of one embodiment of a lightguide 9000 comprisingthe film-based lightguide 107 with coupling lightguides 9001 with lightturning optical edges 8803, light collimating optical edges 8802, andextended regions 7508. The coupling lightguides 9001 can be folded inthe +z direction and translated laterally in the +x direction 8402(shown folded in FIG. 91) such that the coupling lightguides 9001 stackand align above one another.

FIG. 91 is a top view of one embodiment of the lightguide 9000 shown inFIG. 90 with the coupling lightguides 9001 folded and translated to forma stack 9101 of coupling lightguides 9001 such that the stack 9101 ofcoupling lightguides 9001 extends past a lateral edge 8501 of thelightguide region 106 of the film-based lightguide 107. The extendedregions 7508 of the stack 9101 of the coupling lightguides 9001 extendpast the lateral edges 7503 of the coupling lightguides 9001 and thestack 9101 can be cut and/or polished along a cut line 9102 (or adheredto an optical element or light source) without damaging the lateral edge7503.

FIG. 92 is a top view of one embodiment of a lightguide 9200 comprisingthe film-based lightguide 107 with a first set of coupling lightguides8401 and a second set of coupling lightguides 9203 with light turningoptical edges 9230 oriented to turn light in a plurality of directions,and a non-folded coupling lightguide 9201. The coupling lightguides 8401can be folded in the +z direction and translated laterally in the +xdirection 8402 (shown folded in FIG. 93) such that they stack and alignabove one another. The coupling lightguides 9203 can be folded in the +zdirection and translated laterally in the −x direction 9202 (shownfolded in FIG. 93) such that they stack and align above one another.

FIG. 93 is a perspective top view of one embodiment of a light emittingdevice 9300 comprising the light source 102 disposed to couple lightinto the lightguide 9200 shown in FIG. 92 with the first set of couplinglightguides 8401 folded and translated in the +x direction and thesecond set of coupling lightguides 9203 folded and translated in the −xdirection. In this embodiment, the first set of coupling lightguides8401 are folded and translated above the second set of couplinglightguides 9203 which are folded and translated above the non-foldedcoupling lightguide 9201 disposed to receive light from the light source102 and transmit light to the lightguide region 106.

FIG. 94 is a top view of one embodiment of a light emitting device 9400comprising the light source 102 disposed to couple light into thelightguide 9200 shown in FIG. 92 with the first set of couplinglightguides 8401 folded and translated in the +x direction and thesecond set of coupling lightguides 9203 folded and translated in the −xdirection. In this embodiment, the first set of coupling lightguides8401 are folded and translated such that the first set of couplinglightguides 8401 are interleaved with the folded and translated secondset of coupling lightguides 9203 above the non-folded couplinglightguide 9201. In one embodiment, interleaving the couplinglightguides 8401 and 9203 near the light source 102 improves theuniformity of the light within the lightguide region 106 to facilitatepreventing or limiting undesirable variations in light source alignmentand/or light output profile.

FIG. 95 is a top view of one embodiment of a lightguide 9500 comprisingthe film-based lightguide 107 comprising coupling lightguides 8401having light turning optical edges 7502 with the coupling lightguidesextended in shapes inverted along a first direction 9501.

FIG. 96 is a perspective view of one embodiment of folded lightguides9600 comprising the lightguide 9500 shown in FIG. 95. The couplinglightguides 8401 are folded 9602 by translating one end (the top endshown in FIG. 95) in the +z direction, +x, and −y, then the −z directionusing two relative position maintaining elements 2901 to form a stack7501 of coupling lightguides 8401. In a further embodiment, the stack7501 of coupling lightguides 8401 may be cut along cut lines 9601 toform two stacks 7501 of coupling lightguides 8401.

FIG. 97 is a top view of one embodiment of a lightguide 9700 comprisingthe film-based lightguide 107 having coupling lightguides 9702 withlight turning optical edges 8803, light collimating optical edges 8802,and light source overlay tab regions 8301 comprising alignment cavities8302 for registration of the light input surface of the stack ofcoupling lightguides with a light source. The lightguide 9700 alsocomprises a non-folding coupling lightguide 9703 with a collimatingoptical edge 8802, and a light source overlay tab region 8301 comprisingan alignment cavity 8302 for registration of the light input surface ofthe non-folded coupling lightguide 9703 with a light source. Thecoupling lightguides 9702 further comprise curved regions 9701 on theedge of the coupling lightguides 9702 to reduce the likelihood of stress(such as resulting from torsional or lateral bending, for example)focusing at a sharp corner, thus reducing the likelihood of filmfracture. The coupling lightguides 9702 can be folded in the +zdirection and translated laterally in the +x direction 8402 (shownfolded in FIG. 98) such that they stack and align above one another.

FIG. 98 is a top view of one embodiment of a light emitting device 9800comprising the light source 102 (shown in FIG. 99) and the lightguide9700 shown in FIG. 97 with the coupling lightguides 9702 folded andtranslated to form a stack 9803 of coupling lightguides 9702 alignedalong one edge of the lightguide region 106. Light 9802 from the lightsource 102 is collimated by the light collimating optical edges 8802 andhas an optical axis in the −y direction that is rotated by the lightturning optical edges 8803 of the stack 9803 of coupling lightguides9702 to the −x direction and the fold in the stack 9803 of couplinglightguides 9702 redirects the coupling lightguide orientation to the −ydirection such that the light has an optical axis exiting the couplinglightguides 9702 in the −y direction. The light 9802 then propagatesinto the lightguide region 106 of the film-based lightguide 107. Light8702 from the light source 102 has an optical axis in the −y directionand passes through the non-folded coupling lightguide 9703 and into thefilm-based lightguide 107 directly.

FIG. 99 is an enlarged side view near the light source 102 in the y-zplane of the light emitting device 9800 illustrated in FIG. 98. Analignment guide 9903 comprises an alignment arm 9801 that is acantilever spring with a curved front edge disposed above the lightsource 102. The alignment arm 9801 applies a force against the stack9803 of coupling lightguides 9702 to maintain the position of the lightinput surfaces 103 of the coupling lightguides 9702 near the lightoutput surface 9901 of the light source 102. In this embodiment, thealignment arm 9801 is inserted through the alignment cavities 8302 andthe coupling lightguides 9702 can be pulled in the +y direction anddownward (−z direction) such that the alignment cavities 8302 arepositioned over the opposite end of the alignment guide 9803 and thelight source 102 (the free end of the alignment arm 9801 can be liftedslightly during this movement if necessary). In this embodiment, thealignment cavities 8302 register and substantially maintain the positionof the light input surfaces 103 of the coupling lightguides 9702relative to the light output surface 9901 of the light source 102 in thex and y directions and the alignment arm 9801 on the alignment guide9903 maintains the relative position in the z direction by applyingforce in the −z direction to position the stack 9803 of couplinglightguides 9702 against each other and the light source base 9902(which could be a circuit board, for example). Light 9904 from the lightsource 102 exits the light output surface 9901 of the light source 102and propagates into the coupling lightguides 9702 through the lightinput surface 103.

FIG. 100 is an enlarged side view of a region near the light source 102in the y-z plane of one embodiment of a light emitting device 10000comprising an alignment guide 9903 with an alignment arm 9801 that is acantilever spring with a curved edge disposed above a light source 102and light collimating optical element 7102. The alignment arm 9801applies a force against a stack of coupling lightguides 9702 to maintainthe position of the light input surfaces 103 of the coupling lightguides9702 near the light output surface 10002 of the light collimatingoptical element 7102. In this embodiment, the alignment arm 9801 isinserted through the alignment cavities 8302 and the couplinglightguides 9702 can be pulled in the +y direction. In this embodiment,the alignment cavities are not sufficient in length to cover thealignment guide 9903, and the coupling lightguides 9702 remain held inplace in the z direction by the alignment arm 9801. In this embodiment,the alignment cavities 8302 register and substantially maintain theposition of the light input surfaces 103 of the coupling lightguides9702 relative to the light output surface 10002 of the light collimatingoptical element 7102 in the x and +y directions and the alignment arm9801 on the alignment guide 9903 maintains the relative position in thez direction by applying force in the −z direction to position the stack9803 of coupling lightguides 9702 against each other and the lightsource base 9902 (which could be a circuit board, for example). Frictionwith the stack of coupling lightguides 9702 and the light source base9902 and the alignment arm 9801 due to the force from the alignment arm9801 in the −z direction and the friction from the fit of the innerwalls of the cavities 8302 and the light collimating optical element7102 and/or the light source 102 help prevent the coupling lightguides9702 from translating in the −y direction. In another embodiment, thelight input surface 103 of the coupling lightguides 9702 are opticallybonded to the light output surface 10002 of the light collimatingoptical element 7401 (or they are optically bonded to the light outputsurface of the light source 102 or a light turning optical element).Light 10003 from the light source 102 exits the light output surface9901 of the light source 102 and propagates into the light collimatingoptical element 7102 where the light is collimated in the x-y plane andexits the light output surface 10002 of the light collimating opticalelement 7102 and enters the light input surface 103 of the couplinglightguides 9702 where it propagates to the lightguide region 106 (notshown).

FIG. 101 is a cross-sectional side view of a region of one embodiment ofa light emitting device 10100 comprising a stack 7501 of couplinglightguides with interior light directing edges 10101 disposed near theinput edge of the stack 7501 of coupling lightguides and interior lightdirecting edges 10104 disposed near the lightguide region 106 of thefilm-based lightguide 107. Light 10102 from the light source 102 entersthe stack 7501 of coupling lightguides and is reflected and redirectedby the interior light directing edges 10101 disposed near the input edgesurface of the stack 7501 of coupling lightguides. Light 10103 from thelight source 102 is reflected and redirected by the interior lightdirecting edge 10101 disposed near the input edge of the stack 7501 ofcoupling lightguides and further reflected and redirected by theinterior light directing edge 10104 disposed near the lightguide region106 of the film-based lightguide 107.

FIG. 102 is a cross-sectional side view of an embodiment of a lightemitting display 10200 comprising a reflective spatial light modulator10209 and a film-based lightguide 2102 frontlight adhered to theflexible display connector 10206 of the reflective spatial lightmodulator 10209 using an optical adhesive cladding layer 801. Thefilm-based lightguide 2102 further comprises an upper cladding layer10201 on the side opposite the reflective spatial light modulator 10209.The flexible display connector 10206 carries the electrical connectionbetween the display driver 10205 and the active layer 10203 of thereflective spatial light modulator 10209 and is physically coupled tothe bottom substrate 10204 of the reflective spatial light modulator10209. Light 10207 from the side emitting LED light source 10208physically coupled to the flexible display connector 10206 is directedinto the film-based lightguide 2102 and is redirected by lightextraction features 1007 through the optical adhesive cladding layer801, the top substrate 10202 of the reflective spatial light modulator10209, reflects within the active layer 10203, passes back through thetop substrate 10202, the optical adhesive cladding layer 801, thefilm-based lightguide 2102, and the upper cladding layer 10201 and exitsthe light emitting display 10200.

FIG. 103 is a cross-sectional side view of one embodiment a lightemitting display 10300 with a film-based lightguide 10301 physicallycoupled to a flexible display connector 10206 and the film-basedlightguide 10301 is a top substrate for the reflective spatial lightmodulator 10209. Light 10302 from the light source 102 physicallycoupled to the flexible display connector 10206 is directed into thefilm-based lightguide 10301 and is redirected by light extractionfeatures to the active layer 10203 where the light reflects and passesback through the film-based lightguide 10301, and the upper claddinglayer 10201 and exits the light emitting display 10300.

FIG. 104 is a perspective view of one embodiment of a light emittingdevice 10400 comprising a film-based lightguide 2102 physically coupledto the flexible connector 10206 for the reflective spatial lightmodulator 10209 with a light source 102 disposed on a circuit board10401 physically coupled to the flexible connector 10206.

FIG. 105 is a perspective view of one embodiment of a light emittingdevice 10500 comprising a film-based lightguide 2102 physically coupledto the flexible connector 10206 for the reflective spatial lightmodulator 10209 with a light source 102 disposed on the flexibleconnector 10206.

FIG. 106 is a perspective view of one embodiment of a light emittingdisplay 10600 comprising the light emitting device 10400 shown in FIG.104 further comprising a flexible touchscreen 10601 disposed on theopposite side of the film-based lightguide 2102 than the reflectivespatial light modulator 10209. In this embodiment, the film-basedlightguide 2102 extends from the light emitting region 10603 of thelight emitting display 10600 in the −x direction and folds behind thelight emitting region 10603. The flexible touchscreen 10601 extends inthe +y direction from the light emitting region 10603 of the lightemitting display 10600 and folds behind the light emitting region 10603.The flexible touchscreen 10601 further comprises touchscreen drivers10602 disposed on the flexible touchscreen 10601.

FIG. 107 is a perspective view of one embodiment of a light emittingdisplay 10700 comprising the light emitting device 10400 shown in FIG.104 further comprising a flexible touchscreen 10601 disposed between thefilm-based lightguide 2012 and the reflective spatial light modulator10209. In this embodiment, the film-based lightguide 2102 extends fromthe light emitting region 10603 of the light emitting display 10600 inthe −x direction and folds behind the light emitting region 10603. Theflexible touchscreen 10601 extends in the +y direction from the lightemitting region 10603 of the light emitting display 10600 and foldsbehind the light emitting region 10603. The flexible touchscreen 10601further comprises touchscreen drivers 10602 disposed on the flexibletouchscreen 10601.

FIG. 108 is a perspective view of one embodiment of a reflective display10800 comprising a flexible connector 10206 connecting the reflectivespatial light modulator 10209 and the display drivers 10205 on a circuitboard 10401, and further comprising a film-based lightguide frontlightcomprising a film-based lightguide 2102 with coupling lightguides 104folded in a linear fold region 2902 using a relative positionmaintaining element 3301 with substantially linear sections 3303. Therelative position maintaining element 3301 extends past the light inputsurface 103 of the coupling lightguides 104 in a direction (−ydirection) parallel to the optical axis of the light source (+ydirection). Registration pins 10804 physically coupled to the lightsource circuit board 10805 (that is physically coupled to the lightsource 102) pass through alignment openings or apertures in the relativeposition maintaining element 3301 and tab alignment openings orapertures 8101 in the coupling lightguides 104. In one embodiment, theportion of the film-based lightguide 2102 disposed near the reflectivespatial light modulator 10209 and the reflective spatial light modulator10209 are translated and folded 10801 along the fold line 10802 in the+z and +x directions to form a folded light emitting display. Oncefolded, the film-based frontlight 2102 directs light in the −z directiontoward the active display area 10803 of the reflective spatial lightmodulator 10209 and the reflective spatial light modulator 10209reflects a portion of the light in the +z direction.

FIG. 109 is a perspective view of one embodiment of a reflective display10900 comprising a flexible connector 10206 connecting the reflectivespatial light modulator 10209 and the display drivers 10205 on a circuitboard 10401, and further comprising a film-based lightguide frontlightcomprising a film-based lightguide 2102 with coupling lightguides 104folded in a linear fold region 2902 using a relative positionmaintaining element 3301 with substantially linear sections 3303. Therelative position maintaining element 3301 extends past the light inputsurface 103 of the coupling lightguides 104 and the light source 102 ina direction (−y direction) parallel to the optical axis of the lightsource (+y direction). Registration pins 10804 physically coupled to therelative position maintaining element 3301 pass through the tabalignment openings or apertures 8101 in the coupling lightguides 104.The reflective display further comprises a flexible touchscreen film10501 laminated to the film-based lightguide 2102. The touchscreendrivers 10502 and the light source are disposed on the flexibletouchscreen film 10501. In one embodiment, the portion of the film-basedlightguide 2102 and flexible touchscreen film 10501 disposed near thereflective spatial light modulator 10209 and the reflective spatiallight modulator 10209 are translated and folded 10801 along the foldline 10802 in the +z and +x directions to form a folded light emittingdisplay. The film-based frontlight 2102 directs light in the −zdirection and the reflective spatial light modulator 10209 reflects aportion of the light in the +z direction.

FIG. 110 is a top view of one embodiment of a lightguide 11000comprising the film-based lightguide 107 comprising an array of couplinglightguides 104. Each coupling lightguide 104 of the array of couplinglightguides further comprises a sub-array of coupling lightguides 11001with a smaller width than the corresponding coupling lightguide 104 inthe y direction.

FIG. 111 is a perspective top view of one embodiment of a light emittingdevice 11100 comprising the lightguide 11000 shown in FIG. 110. Thecoupling lightguides 104 are folded such that they overlap and arealigned substantially parallel to the y direction, and the sub-array ofcoupling lightguides 11001 are subsequently folded such that theyoverlap and are aligned substantially parallel to the x direction anddisposed to receive light from the light source 102. The sub-array ofcoupling lightguides 11001 couple the light into the couplinglightguides 104 that couple the light into the film-based lightguide107.

FIG. 112 is a cross-sectional side view of a region of one embodiment ofa light emitting device 11200 comprising a stacked array of couplinglightguides 104 comprising core regions 601 and cladding regions 602.The core regions 601 comprise vertical light turning optical edges11201. The cladding regions 602 in the inner regions of the stack ofcoupling lightguides 104 do not extend to the vertical light turningoptical edges 11201 and the core regions 601 are not separated by acladding layer in the region near the light source 102. The light source102 and a light collimating optical element 11203 are disposed at alight input surface 11206 on the stacked array of coupling lightguides104. Light 11207 from the light source 102 is collimated by thereflecting surface 11202 of the light collimating optical element 11203,enters the stack of coupling lightguides 104 and an optical axis 12130of light 11207 is rotated toward the +x direction by the vertical lightturning optical edges 11201 of the core regions 601 of the couplinglightguides. Light 11207 propagates in the core regions 601 near thelight source 102 and totally internally reflects in a core region whenencountering an air gap 11208 or cladding layer 602. In one embodiment,the vertical light turning optical edges 11201 are formed by cutting thestack of core regions 601 at an angle 11205 from a normal 11204 to thesurface of the stack of coupling lightguides 104. In another embodiment,the outer cladding region 602 near the light source 102 does not extendto the region between the light collimating optical element 11203 andthe stack of core regions 601 near the light collimating optical element11203. In another embodiment, the cladding region 602 near the lightcollimation element 11203 is a low refractive index optical adhesivethat bonds the light collimating optical element 11203 to the stack ofcoupling lightguides 104.

FIG. 113 is a cross-sectional side view of a region of one embodiment ofa light emitting device 11300 comprising a stacked array of couplinglightguides 104 comprising core regions 601 and cladding regions 602.The core regions 601 comprise vertical light turning optical edges 11201and vertical light collimating optical edges 11301. The cladding regions602 in the inner regions of the stack of coupling lightguides 104 do notextend to the vertical light turning optical edges 11201 or the verticallight collimating optical edges 11301 and the core regions 601 are notseparated by a cladding layer in the region near the light source 102.The light source 102 is disposed at a light input surface 11206 on thestack coupling lightguides 104. Light 11302 from the light source 102enters the stack of coupling lightguides 104 and is collimated by thevertical light collimating optical edges 11301 of the core regions 601of the coupling lightguides 104. The light 11302 is rotated toward the+x direction by the vertical light turning optical edges 11201 of thecore regions 601 of the coupling lightguides 104. Light 11302 propagatesin the core regions 601 near the light source 102 and totally internallyreflects in a core region 601 when encountering an air gap 11208 orcladding region 602.

FIG. 114 is a cross-sectional side view of a region of one embodiment ofa light emitting device 11400 comprising a stacked array of couplinglightguides 104 comprising core regions 601 and cladding regions 602.The core regions 601 comprise vertical light turning optical edges 11201and vertical light collimating optical edges 11301. The cladding regions602 in the inner regions of the stack of coupling lightguides 104 do notextend to the vertical light turning optical edges 11201 or the verticallight collimating optical edges 11301 and the core regions 601 are notseparated by a cladding layer in the region near the light source 102. Acoupling lightguide 104 near the vertical light collimating opticaledges 11301 defines a cavity 11401. The light source 102 is disposedwithin the cavity 11401 and light 11402 from the light source 102 entersthe stack of coupling lightguides 104 and is collimated by the verticallight collimating optical edges 11301 of the core regions 601 of thecoupling lightguides 104. The light 11402 is rotated toward the +xdirection by the vertical light turning optical edges 11201 of the coreregions 601 of the coupling lightguides. Light 11402 propagates in thecore regions 601 near the light source and totally internally reflectsin a core region when encountering an air gap 11208 or cladding region602. In this embodiment, the cavity 11401 facilitates registration andincreases optical efficiency of the light emitting device 11400. Thecavity 11401 can also serve as an alignment cavity to position the lightsource 102 at a predetermined location (x, y, and +z registration)relative to the vertical light collimating optical edges 11301 and/orthe light turning optical edges 11201. By placing the light source 102within the cavity 11401 of the stacked array of coupling lightguides104, the light flux from the light source 102 directed into the stackedarray of coupling lightguides 104 and remaining in the stacked array ofcoupling lightguides 104 in a total internal reflection condition inareas with the cladding regions 602, or near the lightguide region (notshown) further in the +x direction, is increased relative to a lightsource disposed at the larger outer surface. In another embodiment, thecavity 11401 extends through two or more coupling lightguides 104 orcore regions 601 of the coupling lightguides 104.

FIG. 115 is a perspective view of a region of one embodiment of a lightemitting device 11500 comprising a stacked array of coupling lightguides104 disposed within an alignment cavity 11501 of a thermal transferelement 7002 that is operatively coupled, such as physically coupled, toa base 9902 for a light source (not shown in FIG. 36). The thermaltransfer element 7002 comprises extended fins 7003. Heat from the lightsource disposed within the thermal transfer element 7002 is transferredaway from the light source by the thermal transfer element 7002. Thelight source is disposed to couple light into the stack of couplinglightguides 104. The alignment cavity 11501 can register the stack ofcoupling lightguides 104 in the y and z directions and the light sourcecan provide registration in the +x direction (the coupling lightguides104 are prevented from translating past the light source in the +xdirection). Friction or other mechanical or adhesive means canfacilitate registration and/or maintaining the position of the stacksrelative to the light source 102 in the −x direction (prevent the stackfrom pulling out of the cavity). In another embodiment, an internalridge or an end of the cavity 11501 prevents or limits the lateralmovement of the coupling lightguides 104 in the +x direction andprovides a predetermined minimum distance between the light source 102and the stack of coupling lightguides 104 (which can reduce the maximumoperating temperature at the ends of the coupling lightguides 104 due toheat from the light source).

FIG. 116 is a side view of a region of one embodiment of a lightemitting device 11600 comprising a stacked array of coupling lightguides104 disposed within an alignment cavity 11501 of an alignment guide11601 comprising an extended alignment arm 11602. The stack of couplinglightguides 104 can be inserted into the alignment cavity that registersthe light input surface of the coupling lightguides 104 in the x and zdirections. The inner end 11603 of the alignment cavity 11501 canprovide a stop for the coupling lightguides 104 that sets a minimumseparation distance for the stack of coupling lightguides 104 and thelight source 102. Light 9903 from the light source 102 is directed intothe coupling lightguide 104.

FIG. 117 is a perspective view of one embodiment of a light emittingdevice 11700 comprising a film-based lightguide 11702 and a lightreflecting optical element 11701 (shown in the FIG. 20 as transparent toillustrate the reflecting light ray) that is also a light collimatingoptical element and a light blocking element. The light reflectingoptical element 11701 has a region 11705 that extends beyond thelightguide region 106 and wraps around the stack of coupling lightguides104 and has tab regions 11703 that fold toward the light source 102 toform a light collimating element 11706. Light 11704 from the lightsource 102 is reflected off of the tab region 11703 of the lightcollimating element 11706 and becomes more collimated (smaller angularFWHM intensity) in the y-z and y-x planes and enters the input edges 204of the coupling lightguides 104. Stray light that escapes a couplinglightguide 104 is blocked (reflected or absorbed in this embodiment)from exiting directly from the stack of coupling lightguides 104 by thelight reflecting optical element 11701 that is also a light blockingoptical element. In another embodiment, the light reflecting opticalelement 11701 may be optically coupled to the film-based lightguide11702 by a pressure sensitive adhesive and the light reflecting opticalelement 11701 may diffusely reflect, specularly reflect, or acombination thereof, a portion of the incident light. In a furtherembodiment, the light reflecting optical element 11701 is a low contactarea cover or comprises surface relief features in contact with thefilm-based lightguide 11702.

EXAMPLES

Certain embodiments are illustrated in the following example(s). Thefollowing examples are given for the purpose of illustration, but notfor limiting the scope or spirit of the invention.

In one embodiment, coupling lightguides are formed by cutting strips atone or more ends of a film which forms coupling lightguides (strips) anda lightguide region (remainder of the film). On the free end of thestrips, the strips are bundled together into an arrangement much thickerthan the thickness of the film itself. On the other end, they remainphysically and optically attached and aligned to the larger filmlightguide. The film cutting is achieved by stamping, laser-cutting,mechanical cutting, water-jet cutting, local melting or other filmprocessing methods. Preferably the cut results in an optically smoothsurface to promote total internal reflection of the light to improvelight guiding through the length of the strips. A light source iscoupled to the bundled strips. The strips are arranged so that lightpropagates through them via total internal reflection and is transferredinto the lightguide region. The bundled strips form a light input edgehaving a thickness much greater than the film lightguide region. Thelight input edge of the bundled strips defines a light input surface tofacilitate more efficient transfer of light from the light source intothe lightguide, as compared to conventional methods that couple to theedge or top of the film. The strips can be melted or mechanically forcedtogether at the input to improve coupling efficiency. If the bundle issquare shaped, the length of one of its sides I, is given by I˜√(w×t)where w is the total width of the lightguide input edge and t is thethickness of the film. For example, a 0.1 mm thick film with 1 m edgewould give a square input bundle with dimensions of 1 cm×1 cm.Considering these dimensions, the bundle is much easier to couple lightinto compared to coupling along the length of the film when usingtypical light sources (e.g. incandescent, fluorescent; metal halide,xenon and LED sources). The improvement in coupling efficiency and costis particularly pronounced at film thicknesses below 0.25 mm, becausethat thickness is approximately the size of many LED and laser diodechips. Therefore, it would be difficult and/or expensive to manufacturemicro-optics to efficiently couple light into the film edge from an LEDchip because of the étendue and manufacturing tolerance limitations.Also, it should be noted that the folds in the slots are not creases butrather have some radius of curvature to allow effective light transfer.Typically the fold radius of curvature will be at least ten times thethickness of the film.

An example of one embodiment that can be brought to practice is givenhere. The assembly starts with 0.25 mm thick polycarbonate film that is40 cm wide and 100 cm long. A cladding layer of a lower refractive indexmaterial of approximately 0.01 mm thickness is disposed on the top andbottom surface of the film. The cladding layer can be added by coatingor co-extruding a material with lower refractive index onto the filmcore. One edge of the film is mechanically cut into 40 strips of 1 cmwidth using a sharp cutting tool such as a razor blade. The edges of theslots are then exposed to a flame to improve the smoothness for opticaltransfer. The slots are combined into a bundle of approximately 1 cm×1cm cross-section. To the end of the bundle a number of different typesof light sources can be coupled (e.g. xenon, metal halide, incandescent,LED or Laser). Light propagates through the bundle into the film and outof the image area. Light may be extracted from the film lightguide bylaser etching into the film, which adds a surface roughness that resultsin frustrated total internal reflectance. Multiple layers of film can becombined to make multi-color or dynamic signs.

An example of one embodiment a film based light emitting device that hasbeen brought to practice is described here. The apparatus began with a381 micron thick polycarbonate film which was 457 mm wide and 762 mmlong. The 457 mm edge of the film is cut into 6.35 mm wide strips usingan array of razor blades. These strips are grouped into three 152.4 mmwide sets of strips, which are further split into two equal sets thatwere folded towards each other and stacked separately into 4.19 mm by6.35 mm stacks. Each of the three pairs of stacks was then combinedtogether in the center in the method to create a combined and singularinput stack of 8.38 mm by 6.35 mm size. An LED module, MCE LED modulefrom Cree Inc., is coupled into each of the three input stacks. Lightemitted from the LED enters the film stack with an even input, and aportion of this light remains within each of the 15 mil strips via totalinternal reflections while propagating through the strip. The lightcontinues to propagate down each strip as they break apart in theirseparate configurations, before entering the larger lightguide.Furthermore, a finned aluminum heat sink was placed down the length ofeach of the three coupling apparatuses to dissipate heat from the LED.This assembly shows a compact design that can be aligned in a lineararray, to create uniform light.

A method to manufacture one embodiment of a multilayer frontlightcomprising three film-based lightguides is as follows. Three layers ofthin film lightguides (<250 microns) are laminated to each other with alayer of lower refractive index material between them (e.g. methyl-basedsilicone PSA). Then, an angled beam of light, ions or mechanicalsubstance (i.e. particles and/or fluid) patterns lines or spots into thefilm. If necessary, a photosensitive material should be layered on eachmaterial beforehand. The angle of the beam is such that the extractionfeatures on the layers have the proper offset. The angle of the beam isdictated by the lightguide thickness and the width of the pixels and isgiven by θ=tan⁻¹(t/w), where θ is the relative angle of light to theplane of the lightguide, t is the lightguide and cladding thickness andw is the width of the pixels. Ideally the extraction features direct thelight primarily in a direction toward the intended pixel to minimizecross-talk. Light from red, green, and blue LEDs are input into threelight input couplers formed by folding the coupling lightguides each ofthe three lightguides.

In one embodiment, a light emitting device includes a light sourcehaving an optical axis, a relative position maintaining element, and alightguide comprising a film having a thickness not greater than 0.5millimeters. The lightguide includes a lightguide region and an array ofcoupling lightguides continuous with the lightguide region, wherein eachcoupling lightguide of the array of coupling lightguides terminates inan edge and at least one of the array of coupling lightguides is foldedat least partially around the relative position maintaining element suchthat the edges of the array of coupling lightguides form a stackdefining a light input surface. Light from the light source enters intothe light input surface and propagates by total internal reflectionwithin each coupling lightguide to the lightguide region and therelative position maintaining element extends past the light inputsurface in a direction parallel to the optical axis.

In a particular embodiment, the relative position maintaining elementextends past the light source in a direction parallel to the opticalaxis. 4. The light emitting device may include a light redirectingoptical element positioned to direct the light from the light source tothe light input surface. In a further embodiment, at least one of thelight source and the light redirecting optical element is coupled to therelative position maintaining element.

In a further embodiment, the relative position maintaining elementcomprises an array of guide members and the at least one of the arraycoupling lightguide is folded at least partially around a guide member.In one embodiment, a display comprises the light emitting device and aspatial light modulator, wherein the light emitting device illuminatesthe spatial light modulator.

In another embodiment, a light emitting device includes a light source.A lightguide comprises a film having a thickness not greater than 0.5millimeters. The lightguide includes a lightguide region and an array ofcoupling lightguides continuous with the lightguide region, wherein eachcoupling lightguide of the array of coupling lightguides terminates inan edge and at least one of the array of coupling lightguides is foldedsuch that the edges of the array of coupling lightguides form a stackdefining a light input surface. A light redirecting optical element ispositioned to direct light from the light source to the light inputsurface such that the light propagates by total internal reflectionwithin each coupling lightguide to the lightguide region. The lightredirecting optical element comprises an alignment guide configured toalign the light redirecting optical element to the light input surface.

In a particular embodiment, the alignment guide aligns the lightredirecting optical element to the light input surface in a direction ofthe stack. In a further embodiment, the alignment guide constrains theedges of the coupling lightguides in a direction of the stack. In oneembodiment, the light redirecting optical element is a secondary opticfor the light source. The light redirecting optical element collimatesthe light from the light source such that the light incident on thelight input surface has an angular full-width at half maximum intensityless than 60 degrees in a plane orthogonal to the light input surface.In one embodiment, the light emitting device includes a relativeposition maintaining element comprising an array of guide members andthe at least one of the array of coupling lightguide is folded at leastpartially around the array of guide members.

In a further embodiment, a display comprises the light emitting deviceand a spatial light modulator, wherein the light emitting deviceilluminates the spatial light modulator. In another embodiment, a lightemitting device includes a light source and a lightguide formed from afilm having a thickness not greater than 0.5 millimeters. The lightguideincludes a lightguide region and an array of coupling lightguidescontinuous with the lightguide region, wherein each coupling lightguideof the array of coupling lightguides terminates in an edge and at leastone of the array of coupling lightguides is folded such that the edgesof the array of coupling lightguides form a stack defining a light inputsurface. The light emitting device includes an alignment guide defininga cavity, wherein the light input surface is positioned within thecavity and light from the light source propagates into the light inputsurface such that that the light propagates by total internal reflectionwithin each coupling lightguide to the lightguide region. In oneembodiment, the alignment guide redirects light from the light sourcesuch that the redirected light is more collimated in a first planeorthogonal to an optical axis of the light from the light source. In aparticular embodiment, the first plane is parallel to a direction of thestack. In one embodiment, the light incident on the light input surfacehas an angular full-width at half maximum intensity less than 60 degreesin a plane orthogonal to the light input surface.

In yet another embodiment, a method of manufacturing a light emittingdevice includes separating a plurality of regions in a film with athickness less than 0.5 millimeters to form a plurality of couplinglightguides continuous with a lightguide region of the film, folding atleast one coupling lightguide of the plurality of coupling lightguidessuch that ends of the plurality of coupling lightguides form a stackdefining a light input surface, and positioning a light redirectingoptical element to receive light from a light source and transmit thelight to the light input surface such that the light propagates withineach coupling lightguide to the lightguide region, wherein the lightredirecting optical element comprises one of an alignment guide and acavity defined within the light redirecting optical element configuredto align the light input surface with the light redirecting opticalelement. In a particular embodiment, positioning a light redirectingoptical element comprises positioning the light input surface within thecavity.

Exemplary embodiments of light emitting devices and methods for makingor producing the same are described above in detail. The devices,components, and methods are not limited to the specific embodimentsdescribed herein, but rather, the devices, components of the devicesand/or steps of the methods may be utilized independently and separatelyfrom other devices, components and/or steps described herein. Further,the described devices, components and/or the described methods steps canalso be defined in, or used in combination with, other devices and/ormethods, and are not limited to practice with only the devices andmethods as described herein.

EQUIVALENTS

While the disclosure includes various specific embodiments, thoseskilled in the art will recognize that the embodiments can be practicedwith modification within the spirit and scope of the disclosure and theclaims. Those skilled in the art will recognize, or be able to ascertainusing no more than routine experimentation, numerous equivalents to thespecific procedures described herein. Such equivalents are considered tobe within the scope of the invention. Various substitutions,alterations, and modifications may be made to the invention withoutdeparting from the spirit and scope of the invention. Other aspects,advantages, and modifications are within the scope of the invention.This application is intended to cover any adaptations or variations ofthe specific embodiments discussed herein. Therefore, it is intendedthat this disclosure be limited only by the claims and the equivalentsthereof.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified by the term “about”. Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe foregoing specification and attached claims are approximations thatcan vary depending upon the desired properties sought to be obtained bythose skilled in the art utilizing the teachings disclosed herein.Unless indicated to the contrary, all tests and properties are measuredat an ambient temperature of 25 degrees Celsius or the environmentaltemperature within or near the device when powered on (when indicated)under constant ambient room temperature of 25 degrees Celsius.

What is claimed is:
 1. A display comprising a reflective spatial lightmodulator comprising a front viewing side, a back side opposite thefront viewing side, and an active display area of modulating pixelsenclosed by a plurality of edges on the front viewing side; a frontlightcomprising: a lightguide formed from a film with a thickness less than0.5 millimeters, the lightguide having a lightguide region and an arrayof coupling lightguides continuous with the lightguide region, and thecoupling lightguides of the array of coupling lightguides are folded andstacked such that ends of the coupling lightguides define a light inputsurface; a light emitting region of the film defined within thelightguide region of the film and disposed on the front viewing side ofthe reflective spatial light modulator; and a light mixing region of thefilm between the light emitting region and the array of couplinglightguides, the light mixing region folded around a first edge of theplurality of edges such that the light input surface is positionedbehind the active display area at the back side of the reflectivespatial light modulator; a flexible electrical display connectorextending from the reflective spatial light modulator and folded behindthe reflective spatial light modulator such that the flexible electricaldisplay connector extends behind the active display area at the backside of the reflective spatial light modulator; and a light sourcepositioned behind the active display area at the back side of thereflective spatial light modulator on the flexible electrical displayconnector to emit light into the light input surface.
 2. The display ofclaim 1 wherein the light source and the reflective spatial lightmodulator are electrically driven by electrical connections on theflexible electrical display connector.
 3. The display of claim 2 whereinthe flexible electrical display connector is folded behind a second edgeof the plurality of edges orthogonal to the first edge.
 4. The displayof claim 2 wherein the flexible electrical display connector is foldedbehind the first edge.
 5. The display of claim 3 wherein the lightmixing region of the film is folded to a radius of curvature of lessthan 75 times the thickness of the film.
 6. The display of claim 1wherein the coupling lightguides are physically coupled to the flexibleelectrical display connector.
 7. The display of claim 1 furthercomprising an alignment guide physically coupled to the flexibleelectrical display connector to align the light input surface relativeto the light source.
 8. The display of claim 1 wherein the light sourceis a side-emitting light emitting diode.
 9. A display comprising areflective spatial light modulator comprising a front viewing side, aback side opposite the front viewing side, and an active display area ofmodulating pixels on the front viewing side; a flexible lightguideformed from a film with a thickness less than 0.5 millimeter comprisinga light mixing region of the film positioned along the film between alight emitting region of the film and an array of coupling lightguidesformed from the film and continuous with the film; a flexible electricaldisplay connector extending from the reflective spatial light modulator;and a light source positioned on the flexible electrical displayconnector, wherein the flexible electrical display connector and thelight mixing region of the film are folded behind the reflective spatiallight modulator such that the light source is positioned behind theactive display area at the back side of the reflective spatial lightmodulator, and the light source is positioned to emit light into thearray of coupling lightguides such that the light propagates through theflexible lightguide by total internal reflection and is extracted out ofthe flexible lightguide in the light emitting region on the frontviewing side toward the reflective spatial light modulator.
 10. Thedisplay of claim 9 wherein the light source and the reflective spatiallight modulator are electrically driven by electrical connections on theflexible electrical display connector.
 11. The display of claim 10wherein the coupling lightguides of the array of coupling lightguidesare folded and stacked such that stacked ends of the couplinglightguides define a light input surface positioned to receive lightfrom the light source.
 12. The display of claim 10 wherein the activedisplay area is enclosed by a plurality of edges and the light mixingregion of the film and the flexible electrical display connector arefolded behind one edge of the plurality of edges.
 13. The display ofclaim 10 wherein the active display area is enclosed by a plurality ofedges and the light mixing region of the film is folded around a firstedge of the plurality of edges and the flexible electrical displayconnector is folded behind a second edge of the plurality of edgesorthogonal to the first edge.
 14. The display of claim 10 wherein thefilm is folded behind the reflective spatial light modulator with aradius of curvature of less than 75 times the thickness of the film. 15.The display of claim 10 wherein the coupling lightguides are physicallycoupled to the flexible electrical display connector.
 16. The display ofclaim 1 further comprising an alignment guide physically coupled to theflexible electrical display connector to align the light input surfacerelative to the light source.
 17. The display of claim 1 wherein thelight source is a side-emitting light emitting diode.
 18. A method ofmanufacturing a display, the method comprising: forming a flexiblelightguide from a film with a thickness less than 0.5 millimetercomprising a light mixing region of the film positioned along the filmbetween a light emitting region of the film and an array of couplinglightguides formed from the film and continuous with the film;positioning a light source on a flexible electrical display connectorextending from a reflective spatial light modulator; positioning thelight emitting region of the film on a front viewing side of thereflective spatial light modulator opposite a back side; folding thelight mixing region of the film and the flexible electrical displayconnector behind the reflective spatial light modulator such that thelight source is positioned behind the reflective spatial light modulatorat the back side of the reflective spatial light modulator and ispositioned to emit light into the coupling lightguides such that thelight propagates through the coupling lightguides and light mixingregion by total internal reflection and is extracted out of thelightguide in the light emitting region on the front viewing side towardthe reflective spatial light modulator.
 19. The method of claim 18wherein folding the light mixing region of the film and the flexibleelectrical display connector behind the reflective spatial lightmodulator includes folding the flexible electrical display connector andthe light mixing region of the film around a first edge of an activedisplay area of the reflective spatial light modulator.
 20. The methodof claim 18 wherein folding the light mixing region of the film and theflexible electrical display connector behind the reflective spatiallight modulator includes folding the flexible electrical displayconnector behind a first edge of an active display area of thereflective spatial light modulator and folding the light mixing regionof the film around a second edge of the active display area orthogonalto the first edge.